Some economists predict that the dollar will remain weak _______ economies abroad are expected to grow faster than that of the United States.
| A．while | B．as | C．before | D．until |
_____his father had come, his face lit up.
| A．Having learned | B．When he learned | C．Heating | D．When learning |
______, they would certainly come and help us.
| A．Had they time | B．Do they have time | C．Had they have time | D．Did they had time |
-How long ______ each other before they ______ married?
--For about a year.
| A．have they known; get | B．have they known; were going to get |
| C．do they know; are going to get | D．had they known; got |
Smith ______ a book about China last year, but I don't know whether he has finished it.
| A．has wrote | B．wrote | C．had written | D．was writing |
I paid him $ 50 for the painting , but its true ___ must be least $500.
| A．price | B．money | C．value | D．importance |