Only ______according to the directions can the medicine be quite effective.
| A．taking | B．taken | C．being taken | D．having been taken |
John opened the door. Therehe had never seen before.
| A．a girl did stand | B．a girl stood |
| C．did a girl stand | D．stood a girl |
—Is Bob still teaching?
—I’m afraid not. He is saidthe school as he has become a businessman.
| A．that he has left | B．to leave |
| C．to have left | D．to be left |
—I wonder how much you charge（要价） for your services.
—The first two are freethe third costs￥30.
| A．while | B．until | C．when | D．before |
The discovery of the stolen car led to.
| A．the thief having caught | B．the thief catching |
| C．the thief being caught | D．the thief to be caught |
is known to us all is that the 2012 Olympic Games will take place in London.
| A．It | B．What | C．As | D．Which |