The elephants ought ______ hours ago by the keepers.
a. to be fed b. to feed c. to being fed d. to have been fed
What is known to all is that up to now China has made a great___________ to preserving the peace.
| A．conclusion | B．comment |
| C．campaign | D．contribution |
---Did you remember to take the key to Tom?
---Yes, I gave it to him ________ I saw him.
| A．while | B．once | C．suddenly | D．the first time |
It is ________ world of wonders, ________ world where anything can happen.
| A．a; a | B．a; the | C．the; the | D．the; a |
Father ________ for London on business upon my arrival, so I didn’t see him.
| A．has left | B．left | C．had left | D．was leaving |
The boy’s dream was to have his own laboratory ________ to try out some of his own ideas.
| A．from which | B．in which |
| C．by which | D．at which |