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Could you please help me make these sentences grammatical?

1 I have to watch another 3 episodes until I'm up to speed with the show.
2 I got there as/while the train was pulling in for once.
3 Trains don't come around that often on holidays.
4 I have no particular order or time at which to do my tasks at work. Some nights I might do task A at 10am other nights I might do it at 11am and someone nights I might do task B before task A.
5 If you had played it once you would have lost all your money, but every time you did it an extra time, you won a bigger/higher percentage of the pot.
6 His hair looks better as it gets greasier/The greasier his her, the better it looks.
7 The deaths probably have (something) to do with the house.
8 Do you know how long I can't have contact lens (for
9 When I watch movies on my computer, my processor heats up abnormally.

10 Witch: I have the ability to make you young, but someone has to get old for me to give you years back.
Person : People are dying while others are becoming young studs again. Is that what you do you, witch.

Thank you
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Here are my suggestions.

1 I have to watch another 3 episodes until I'm up to speed with the show. (Okay)

2 I got there as/while the train was pulling in for once. (I prefer "as")

3 Trains don't come around that often on holidays.
"Come around" seems the wrong verb. Perhaps you want "arrive." Trains don't arrive as often during the holidays. Or: Trains are less frequent during the holidays.

4 I have no particular order or time at which to do my tasks at work. Some nights I might do task A at 10am other nights I might do it at 11am and someone nights I might do task B before task A.
The first sentence is not quite right and the second sentence needs breaking up. "I have no particular order or time for doing my tasks at work. On some nights I might do task A at 10 am. On other nights I might do it at 11 am. And some nights I might do task B before task A."

5 If you had played it once you would have lost all your money, but every time you did it an extra time, you won a bigger/higher percentage of the pot.
If you had played it once, you would have lost all your money. Instead, each time you played an extra round, you won a bigger percentage of the pot.

6 His hair looks better as it gets greasier/The greasier his her, the better it looks.
Either way (but "hair" not "her").

7 The deaths probably have (something) to do with the house.
I would use "something" but a more exact verb would be better. The deaths probably are connected to the house. (The house causes the deaths? The house is a prize that people are killing for? What?).

8 Do you know how long I can't have contact lens (for
I am not sure what you want to say here. "Do you know how long before I can have contact lens?"

9 When I watch movies on my computer, my processor heats up abnormally. (Okay)

10 Witch: I have the ability to make you young, but someone has to get old for me to give you years back.
Person : People are dying while others are becoming young studs again. Is that what you do you, witch.
I would change the wording around:
Witch: I have the ability to make you young, but in order to give you your years back, someone else has to get older.
Comments  
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Hi Doctor D,

Can you say

Trains arrive more often during the weekends.

Thanks
You could, but it might be better to say:

More trains arrive on the weekend (than during the week).
What about?

Trains arrive more often on the weekends.

How come it is not correct to say

come around often...?
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Yes, your first sentence also works.

As for "come around"
Trains don't come around. They arrive or depart. People come around.