—Mr. Smith, why are you always asking me to do the difficult work?—Because you _______ do such a thing and nobody else is fit for it.

–– ________ I come back before 6 o’clock?–– No, you _______ . But you ______ be back later than 7 o’clock.

Some aspects of a pilot’s job__________ be boring, and pilots often ________ work at inconvenient hours．

－Thank you for your gift. －________________

 --- You needn’t take an umbrella. It isn’t going to rain.--- Well, I don’t know. It     do.