—The research on the new flu virus vaccine is challenging and demanding. Who do you think can do the job?     —______ my students have a try?

(2013·湖南高考)He ________ sleep, although he tried to, when he got on such a hunt for an idea until he had caught it.

He           have completed his work; otherwise, he wouldn’t be enjoying himself by the seaside.

(   )28.－_____ you put away your books?－Yes, mum. I’ll do it at once.

In China's countryside, villagers often have the same family name, but ________ not be closely related.