“be+形容词”构成祈使句 只有表示一时的行为的形容词才可用于 be / dont be 之后，如careful / careless, patient / impatient, quiet, silly 等(be / dont be 通常不行与指状态的形容词连用，如 hungry / thirsty, pretty)。如：Be quiet! 清静点！Dont be silly! 不要发傻！Do be patient. 确定要有耐烦。Be careful about what you say. 说话要当心。Be more careful with your work. 你的工作要再细心一些。Be careful not to break anything. 留神别打破什么了。Be sure you dont break any of them. 千万别把它们打破了。Be sure to write to ma as soon as you get there. 到了千万给我来信。Be sure and come as soon as possible. 确定要尽快来。Be sure to send out all the invitations today. 确定要在今日把请帖都发出去。留意有关的回答Be quiet! 别说话!否认的回答：I wont! 我不嘛!Dont be so impatient! 别这么焦急!否认的回答：Im not! 我不焦急!
