1 can't 是can的否定式,表示能力上的不夠或不足,指沒有能力做某事,或者不可能做某事。
He can't move the stone. 他搬不動這塊石頭。
She can't come today. 她今天不能來。
2 mustn't 表示“千萬不要,絕對不可,不許可”,指的是不允許做某事,或堅決不讓做某事。
You mustn't swim in that river. 你絕對不可去那條河里游泳。
你不能離開,外面在下大雨 。
You can't leave. It's raining hard outside. (誤)
You mustn't leave. It's raining hard outside. (正) (這里的“不能”不是表示能力或可能,而是表示“絕不可” )
你們不能吵吵嚷嚷,孩子們在做作業(yè) 。
You can't make a noise. The children are doing their homework. (誤)
You mustn't make a noise. The children are doing their homework.(正)
(這里的“不能”意為“不許可” )
提示
must never意為“千萬不可”,比mustn't語氣更重。
You must never lend money to him. He won't pay you back. 你千萬不要把錢借給他,他不會還你的。