Beijing took steps to limit the kinds of high-risk of borrowing money from the banks that can create the high price of housing, ______ happened in the United States．
a．as B．that C．how D．while
This old professor insisted that he _____energetic enough and that he _____．
| A．be, shouldn’t retire | B．was, not retire |
| C．should be, shouldn’t retire | D．was, should retire |
The living room is clean and tidy, ________ a dining table already laid for a meal to be cooked.
| A．as | B．which | C．with | D．That |
Scientists say it will be five or six years ________ it is possible to test this medicine on humans．
| A．after | B．before | C．since | D．When |
You are students in the No.168 Senior High School now, but you _______ in different junior high schools for three years．
| A．studies | B．have studied |
| C．studied | D．were studying |
Being injured in the leg made _______ impossible for him to walk his way home．
| A．that | B．which | C．it | D．One |