Choose the correct word:
17.can/should i ask you a question?
18.will/shall we go out for lunch today?
19.you must/shouldn't stay at home if you are all.
20.tommy can't/couldn't tell the time when he was a baby.
21.my book can't/mustn't be in the house.i've looked everything.
22.you haven't/needn't clean the windows.i've already done them.
23.sam left late for the airport this morning.he should/could have missed his flight​