All these sentences have a mistake. Correct them

II.               All these sentences have a mistake. Correct them.

1.               You needn’t to worry about losing your jobs.

2.                I think I saw her go out, so she might be at home.remember to post it.

3.               We needn’t allow our competitors to gain an advantage over us.

4.               When the students have question, they must to raise their hand.

5.               We have enough food at home, so we mustn’t go shopping today.

6.               It mightn’t be true. There must be some mistake.

7.               You mustn’t work at weekends for the moment

8.               Many students would rather to study on their own than go to class.

9. If we don’t get to the market soon they can’t have any flowers left. They will all have been sold.