---What do you think of the book?
---Oh,excellent. It's worth____a second time.
A. to read B.to be read
C, reading D,being read
_________ environmental damage is done, it takes many years for the ecosystem to recover.
| A．Even if | B．If only | C．While | D．Once |
After he became conscious, he remembered _________ and _________ on the head with a rod.
| A．to attack; hit | B．to be attacked; to be hit |
| C．attacking; be hit | D．having been attacked; hit |
Human facial expressions differ from those of animals in the degree _________ they can be controlled on purpose.
| A．with which | B．of which | C．to which | D．for which |
David and Susan didn’t give in to each other, so they _________ the whole time they were together.
| A．have quarrelled | B．had quarrelled |
| C．were quarrelling | D．had been quarrelling |
At a rough estimate, Nigeria is _________ Great Britain.
| A．three times the size as | B．the size three times of |
| C．three times as the size of | D．three times the size of |