Which are the correct answers?

Hi!

I recently answered an online test about English Grammar, consisted of 50 questions.

I scored 86%. There were some answers I only guessed and suppose that these were my mistakes.

I include them below. Could you please tell me the correct answers?

Thanks in advance!

1. There is something you want to say, ...

Choose one:

a isn't there?

b isn't it?

c doesn't it?

I chose a.

2. The guide ... visiting the Royal Palace.

Choose one:

a suggested

b agreed

c promised

I chose a

3. Here ...

Choose one:

a the postman comes.

b comes she.

c comes the bus.

I chose a.

4. It ... have been Carla you saw this morning. She is away on holiday.

Choose one:

I chose b

5 Mike insisted ... his new muffin recipe.

Choose one:

I chose c

6 Where would you rather ...

Choose one:

I chose c