_______ is necessary for you to lock the car when you don’t use it.
| A．What | B．This | C．It | D．That |
—We’ve had three whole weeks without a drop of rain.
—True. No crops will _____ if the dry weather continues.
| A．select | B．survive | C．explode | D．remove |
There might be life on other planets, but so far scientists haven’t found enough _____ to prove it.
| A．evidence | B．relic | C．mystery | D．reception |
They are having _____ debate about whether the two countries were at _____ war at the time.
| A．the; the | B．a; the | C．the; 不填 | D．a; 不填 |
I refuse to lie about it, because it’s against my _____.
| A．rules | B．orders | C．principles | D．laws |
The buses, _____ were already full, were surrounded by anxious people.
| A．all of them | B．all of which | C．they all | D．all which |