Can You Pick The Right Answer And Explain Why ?

Anybusy;

Please pick your answers first. Then we can comment on them.

You will learn much more from the exercise by following Alpheca's advice.

The one with the star is the correct answer! Can you explain to me why? Thanks!

I don't know if I can do it but I'll ____ a go.

*have
make
give

He ____ gone to work yesterday. John was there all day and nobody saw him.

mustn't have
*can't have
wasn't have

Can you tell me when ____ leaving?

does the plane
*the plane is
is the plane

Argentina, ____ is well-known for its mountains, is a very popular with ski-tourists.

*which
that
who

This fish is ___ delicious.

very
*really
completely

It's about time we ___ - it's nearly midnight

leave
*left
to leave

andybusyI don't know if I can do it but I'll ____ a go.

I'll __give it__ a go.

Make a go is not idiomatic.

Have a go must be British English. I use "give it a go."

andybusyHe ____ gone to work yesterday. John was there all day and nobody saw him.

As an American English speaker, I use mustn't have or couldn't have, and rarely, can't have. British English apparently uses can't have.

andybusyCan you tell me when ____ leaving?

Indirect questions use the normal subject-verb order.

andybusyArgentina, ____ is well-known for its mountains, is a very popular with ski-tourists.

Nonessential (non-defining, non-restrictive) relative clauses, which are set off by commas, do not use "that."
Who refers to people.

andybusyThis fish is ___ delicious.

I have no problem with very or really.

andybusyIt's about time we ___ - it's nearly midnight

Subjunctive mood showing a suggestion for action.
Here are some examples of the subjunctive:
http://www.ceafinney.com/subjunctive/examples.html

AlpheccaStarsHave a go must be British English

It is.

AlpheccaStarsAs an American English speaker, I use mustn't have or couldn't have, and rarely, can't have. British English apparently uses can't have.

Yes. For us, can't have is the most likely; couldn't have is possible; mustn't have is pretty unlikely.

andybusyIt's about time we ___ - it's nearly midnight

For me, both leave and left work here.

Aspara Gus andybusyIt's about time we ___ - it's nearly midnightFor me, both leave and left work here.

That would be completely wrong in BrE. For us, it's:

It's (about/high) time we left.
It's (about/high) time (for us) to leave.

To Fivejedjon

What is the different between using to leave and left, one is using "infinitive to" and the other is using a past participle to describe an action in here!?

Can you further explain your point of view in here by using the two different verb form(to leave/left), also what is the meaning of saying It's (high) time we left?

Cheers

Andy