Remove the batteries when they become weak or when the unit is not in use for extended periods. This will damage to the unit from battery leakage at such times.
| A．disappoint | B．concern | C．instruct | D．prevent |
John invited about 40 people to his wedding, most of _____ are family members.
| A．them | B．that | C．which | D．whom |
______ surprised the hostess most is _______ one of her friends left the party without saying a word.
| A．What, what | B．What, that |
| C．That, that | D．That, what |
_____ is even important _____ as the earth cooled down, water began to appear on its surface.
| A．That, which | B．What, that |
| C．What, what | D．It, that |
I don’t think she will come to the meeting on time, ______?
| A．do I | B．do you |
| C．will she | D．won’t she |
We don't imagine the twins have arrived, _____?
| A．do we | B．have they |
| C．don’t we | D．haven’t they |