Объяснение:
2.1 They must visit Australia
2.2 You mustn't throw rubbish
2.3 You mustn't drink here
2.4 I must do my homework every day
3.1 I haven't travelled by plane before
3.2 He has never done his homework
3.3 Jessy has already visited the White House
3.4 Have they gone to the skating rink today?
3.5 This week I have read a French book
