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I don't believe he should have to tell you the truth. <-- Do I need to add a "that" after "believe" ? When can I omit "that" in a sentence ? and when I can't ?

The group will have to share the responsiblities of the decision.
= the group shall share the responsiblities of the decision.

Everybody has (can I also use "have" here since the word "everybody" means a bunch of people?) to submit their assignment ( should I use "assignemnts" instead? However, it's so confusing since one assignment per person; If I put "assignments", it could also mean that there are more than one assignment per person for submission.) tomorrow. <-- Please help me to clarify this, Many thanks.

I clean the house more often than you do. = "I have cleaned the house more often than you have." Any differences in meaning?

He lost his wallet while he was hiking.
He lost his wallet when he was hiking. <-- what's the difference between "when" and "while" ?

Is the 2nd one of the following pairs also correct grammar-wise? If yes, any differences in meaning?

When did you buy that book?
When have you bought that book?

He talks as he knows everything.
He talks as he knew everything.

I had been working three hours before I suddently became sick.
I had worked thress hours before I suddently became sick.

The apples sold at the store are very fresh.
The apples selling at the store are very fresh

I hope she gets well soon.
I hope she will get well soon

I had never seen such a beautiful house.
I have never seen such a beautiful house.

You should try learning a little French before visiting Paris.
You should try to learn a litle French before visiting Paris.

Would you mind shutting the door?
would you mind to shut the door?

My father finds it difficult to write in English.
My father finds it difficult writing in English.

Please help me to correctly use " to " form and "-ing" form. Thanks.
Comments  
I don't believe he should have to tell you the truth. <-- Do I need to add a "that" after "believe" ? No. When can I omit "that" in a sentence ? and when I can't ? You cannot omit that when it is a relative pronoun functioning as the subject in its relative clause. Otherwise you can omit it.

The group will have to share the responsiblities of the decision.
= the group shall share the responsiblities of the decision. No. These are not the same.

Everybody has (can I also use "have" here since the word "everybody" means a bunch of people?) to submit their assignment ( should I use "assignemnts" instead? However, it's so confusing since one assignment per person; If I put "assignments", it could also mean that there are more than one assignment per person for submission.) tomorrow. <-- Please help me to clarify this, Many thanks.
Everybody has to submit their assignment is fine. Never *Everybody have ... Use their assignments if each has more than one.

I clean the house more often than you do. = "I have cleaned the house more often than you have." Any differences in meaning? Yes. I clean ... these days; I have cleaned ... in the past.

He lost his wallet while he was hiking. < This is the better of the two.
He lost his wallet when he was hiking. <-- what's the difference between "when" and "while" ? when introduces an event; while introduces an activity. when tells 'at which moment in time'; while tells 'during which period of time'. But it's not uncommon for when to be used like while if the speaker conceptualizes the activity as an event.
Below, note that reading and walking are activities; walking into a room and finding money are events.

Susan was reading when Mike walked into the room. Mike walked into the room while Susan was reading.
Bob was walking in the park when he found the money. Bob found the money while he was walking in the park.

And when also introduces states. When I was young, When I was a student, When I am tired, When I was married, ...

Is the 2nd one of the following pairs also correct grammar-wise? If yes, any differences in meaning?

When did you buy that book?
When have you bought that book? Not semantically coherent. Don't use present perfect with a definite time (When?).

He talks as if he knows everything.
He talks as if he knew everything. Weaker, but basically the same meaning.

I had been working three hours before I suddently became sick. (suddenly)
I had worked three hours before I suddently became sick. No significant difference. The first is a more vivid description, perhaps.

The apples sold at the store are very fresh.
The apples selling at the store are very fresh Again, the progressive makes it more lively and immediate.

I hope she gets well soon.
I hope she will get well soon No significant difference. The first is more often said, I'd say.

I had never seen such a beautiful house. (until some time in the past)
I have never seen such a beautiful house. (until now)

You should try learning a little French before visiting Paris.
You should try to learn a little French before visiting Paris. No significant difference. The first is less insistent, perhaps.

Would you mind shutting the door? OK.
would you mind to shut the door? Not correct.

My father finds it difficult to write in English. OK.
My father finds it difficult writing in English. Not correct.
Please help me to correctly use " to " form and "-ing" form. Try searching "catenative verbs" on this site on on Google. Each combination has to be learned separately.

CJ
Many thanks indeed for all your help, Jim. Could you also kindly help me with the further questions? Thank you !

The group will have to share the responsiblities of the decision.
= the group shall share the responsiblities of the decision. No. These are not the same

Why are they not the same? " will have to" = "shall" ?

I clean the house more often than you do. = "I have cleaned the house more often than you have." Any differences in meaning? Yes. I clean ... these days; I have cleaned ... in the past.

"these days" also means the days in the past, right? then why are they not the same in meaning?

" Gentlemen, please pass me the original copy of all contracts retained by the ( can I omit "the" here? why?) clients." Is this correct? (Please note there is only one original copy.)

"Gentlemen, please pass me all the original copies of all contracts retained by the clients." Does this mean that there are more than one original copy of all contrac

Students: Are you brave enough to let our tutors analyse your pronunciation?
The group will have to share the responsiblities of the decision.
= the group shall share the responsiblities of the decision. No. These are not the same

Why are they not the same? " will have to" = "shall" ?
will (= shall) indicates the future. We will share the responsibilities. = We shall share the responsibilities. The sharing of responsibilities takes place in the future. Nothing will stop it.
will have to means that a necessity or an obligation (to do something) will occur in the future; it doesn't mean that what is necessary or obligatory will occur. We will have to share the responsibilities. = We shall have to share the responsibilities. In the future, the sharing of responsibilities will become a necessity.
By the way, shall is hardly ever used in American English. We almost always use will instead.
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I clean the house more often than you do. = "I have cleaned the house more often than you have." Any differences in meaning? Yes. I clean ... these days; I have cleaned ... in the past.

"these days" also means the days in the past, right? then why are they not the same in meaning?
Although these days includes recent days in the past, the emphasis is on the current situation, not on a past situation. But there is another way to think about this. Consider this:
Sometimes the very same situation can be described in different ways. I can say "Three is less than five." or I can say "Five is greater than three." This is the same fact, but looked at in different ways.

Something similar happens with the sentences about cleaning. If I want to point to my accomplishments in the past (compared to yours), I say I have cleaned the house more often than you have. There is no reference to anything but past accomplishments, so there is no implication at all about my present or future behavior. On the other hand, if I want to emphasize what a good worker I am (now) (compared to you), I say I clean the house more often than you do. This implies that I have always been a better worker than you, that I am a better worker than you, and that I will probably continue to be a better worker than you. The sentence I clean the house more often than you do describes a behavior that is in effect now. It makes a general statement about my cleaning. And the sentence I have cleaned the house more often than you have is the evidence that supports the generalization. Because you can see that, in specific instances, I have cleaned the house more often than you have, we can make the generalization that I clean the house more often than you do.
If, in specific cases, I have read fewer books than you (in the past), then we can generalize that, as things stand now, I read fewer books than you. (I am not [not was not] as avid a reader as you, judging from the evidence.)

If, in specific cases, you have earned more money than I, then we can generalize that, as things stand now, you earn more money than I. (You regularly receive [not received] more money for your work than I do for mine, judging from the evidence.)

And so on.

This explanation will not automatically clear up all the difficulties. Don't expect it to. But with more and more experience with many more sentences in different situations, you'll eventually understand.
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" Gentlemen, please pass me the original copy of all contracts retained by the ( can I omit "the" here? why?) clients." Is this correct? (Please note there is only one original copy.)

Yes. I would keep "the".

"Gentlemen, please pass me all the original copies of all contracts retained by the clients." Does this mean that there are is more than one original copy of all contrac
Yes. original copies means there is more than one original copy.
CJ
Jim, could you also help me to understand the following questions regarding VERB forms? Many thanks.

May I call on you tomorrow afternoon? = " May I call you tomorrow afternoon?" ? any differences in meaning?

She was almost run down by a drunk driver.= "She was almost run over by a drunk driver" ?

"Few people admit that they are wrong." Is this correct? Why? Is it equal to " Few people admit that they can be wrong." ?

Would you mind if I called ( can I also use "call" here? Why? )you by your first name?

The criminal fled (why I can't use "had fled" since it started and finished in the past ?) after having murdered the old man.
= The criminal fled after having the old man murdered.?
= The criminal fled after he murdered the old man. ?

I'm used to jogging ( why not "jog"?) in the partk every other day.

They might have been there, but I didn't see them.

They might be there, but I didn't see them. <-- Is this correct? Any differences in meaning?

I expect that he will get well soon.
I expect that he gets well soon. <-- why this is incorrect?

Toronto is very beautiful when there is (can I also use "was" here?) a lot of snow.
Toronto could be very beautiful when this was a lot of snow. <-- Is this correct?

When I got (can I also use "arrived"?) to (can I also put "the" here?) class, many students were absent.

Did you finish your homework?
Did you finish doing your homework? <-- this is more focused on the "doing" part, right?

I'm hungry because I haven't had breakfast or lunch.
I'm hungry because I didn't have breakfast or lunch <-- Is this correct? Any differences in meaning?

Don't worry. She is used to living ( why not "live"?) by herself.

He revealed having written the letter to her. <-- is this correct?
Please start a new thread with these. It is also better to ask fewer questions in each post. Otherwise you discourage people from answering.

Thanks. Emotion: smile

CJ
Teachers: We supply a list of EFL job vacancies
Okay, I will. Thank you for all your.

Sarah