The world’s population is getting larger and larger, so scientists will have to ______ new ways to solve food problem.
| A．catch up with | B．keep up with | C．come up with | D．make up with |
We didn’t start our discussion _____ everybody arrived.
| A．since | B．if | C．while | D．until |
Take the exam carefully, _____ you won’t get full marks.
| A．but | B．and | C．or | D．so |
We hope that with the help of the new skill, Liu Xiang can run _____ than before.
| A．fast | B．faster | C．fastest | D．the fastest |
The students from Xinjiang enjoy staying in our school because everyone is _____ to them.
| A．friendly | B．gently | C．happily | D．politely |
The old man used to raise many _____ to make a living on the farm.
| A．duck | B．horse | C．bird | D．sheep |