1.can 可能，可以，、can I sit here? yes ,you can.can't 、不能，不会 ，表示能力。I can't speak English.can be 、可能会，表示理论上的可能性 The weatherin north China can be a little colder than that in the south.can't be不可能是表示否定推断。it can't be his sweater,because his is black. 2.must 、必需，一定 you must study hard.mustn’t、一定不要，you mustn't play with fir...
