__________ he took part in the competition, he won a second prize.
| A．The first time | B．For the first time |
| C．At a time | D．At one time |
The atomic weight of oxygen is_____than ______of the hydrogen.
| A．15 times heavier; that |
| B．15 times heavier: those |
| C．16 times as heavier; that |
| D．16 times as heavy; those |
In Singapore, people______eating or drinking on the subway can be fined up to 500 Singapore dollars.
| A．having caught | B．catching |
| C．caught | D．to catch |
The zookeeper was really annoyed with me.
— How could he have been if you______stones at the animals?
| A．didn’t throw | B．don’t throw |
| C．hadn’t thrown | D．haven’t thrown |
—What do you do as a volunteer in North Africa?
—__________! There are many poor people who need a lot of help.
| A．None | B．Something |
| C．Little | D．Everything |
They’ve moved to a different house_________their children can attend a better school.
| A．in case | B．so long as |
| C．so that | D．even though |