Question

must的否定句是mustn't还是needn't

Answer 1

must务必（表命令），否定式mustn't
must必须（表必要性），否定式needn't
must肯定（表猜测），否定式can't
You mustn't leave.你不准离开。
You needn't clean the window.你不必清洁窗子。
He can't be in the classroom now.
他现在不可能在教室里。