Look at the sign!It says No Smoking.You____smoke here填shouldn't还是mustn't
问题描述：
Look at the sign!It says No Smoking.You____smoke here填shouldn't还是mustn't
答
mustn't 表示禁止,语气很强烈
shouldn't 更多用于虚拟语气句等中,也是will的否定,意思为不应该