15. --- Who are the teenagers gathering at the school gate?
--- Well, if you _____ know, they are all my visiting students.
| A．need | B．must | C．may | D．Will |
—I plan to pay a visit to Peter this Sunday．
—I agree. You know, he ________come to see us on Sundays when we were in USA.
A. might B. would C. should D. could
--- It’s more expensive to live in the city than to live in the country, I think.
--- ____ . Living in the city brings people better conditions, though.
| A．That’s all right. | B．I’m sorry to hear that |
| C．That is really necessary | D．I couldn’t agree more. |
____ abroad for two years, the two astronauts went back home last year.
| A．Educating | B．Educated | C．Having been educated | D．being educated |
________ the normal condition, he can read 150 words a minute.
| A．Below | B．Under | C．With | D．In |
He left ________any of his friends _________ him _________.
| A．with; seeing; of | B．without; seeing; off |
| C．without; see; / | D．with; see; out |