It's OK to________an electrical appliance on so long as you are using it.
| A．leave | B．make |
| C．turn | D．open |
It was a matter of________ would take the position.
| A．who | B．whoever | C．whom | D．whomever |
In China, all the students work hard at school _________ going to university for higher education in the future.
| A．in the habit of | B．in the hope of |
| C．in search of | D．in honor of |
Robert is said ___________ abroad, but I don’t know what country he studied in.
| A．to have studied | B．to be studying |
| C．to study | D．to have been studying |
He made another wonderful discovery, ______ of great importance to science.
| A．which I think is | B．which I think it is |
| C．which I think | D．I think which is |
Was it through Mary,_____ was working at a high school, ____ you got to know Tom?
| A．who; who | B．that; which | C．who; that | D．who; which |