用can/can't;must/mustn't填空
1.You ____ leave school at the age of 14.
2.---____you go swimming with us this afternoon?
---Sorry,I ____.I ____ take care of my little sister at home because my mother is ill.
3.Look out!The knife is very sharp.You ____ cut your finger.
4.You ____ leave Chinese without a passport.
5.You ____ go and ask Meimei.She ____ know the answer.