1£®They ____________ stay in the office last night because of the snowstorm.(have to/must)

2£®You ____________ have spent so much time playing computer games.(mustn't/oughtn't to)

3£®I want to go to the office, but you ____________(need not to go/need not go) with me.

4£®He went on foot, but he ____________(ought to go/should have gone) by bus.

5£®You_________go there alone; it's too dangerous.(mustn't/needn't)

6£®It's so near; we ____________ have taken a taxi.(shouldn't/can't)

7£®—Shall I leave the room so that you two can talk?

—No, you ____________.(mustn't/needn't)