mustn't or needn't

1) I needn't* take the umbrella. It won't rain.*
2) I mustn't* cross this bridge. It's closed.*
3) We mustn't* be late. The train will leave in 10 minutes.*
4) You needn't* hurry. We have plenty of time.*
5) You mustn't* smoke in here. It's forbidden. Look at that sign.*
6) We have enough diesel, so we needn't* stop here.*
7) You needn't* come if you don't want to.*
8) They needn't* do the washing up, they have a dishwasher.*
9) You mustn't* show this e-mail to anyone else. I'll trust you.*
10) The students mustn't* forget their homework.*

FOCUS GRAMMAR VI