By the time Billy was 6, he in the sea.
| A．had already swum | B．was already swimming |
| C．has already swum | D．already swam |
Taxi is one of the most common means of city transport, so the increase of taxi _______ in Hangzhou has led to much public concern.
| A．fee | B．charge | C．fare | D．cost |
In order to gain a bigger _______ in the Chinese mobile phone market, Apple Inc. tries its best to make the phones more and more attractive.
| A．challenge | B．share | C．balance | D．choice |
There are a large number of plants existing on earth, however, very little _______ was made of them to feed us.
| A．cost | B．value | C．use | D．matter |
--- I’m terribly sorry, but I made a mistake again.
--- _______. Practice more and you’ll succeed.
| A．Never mind | B．Certainly not | C．You’re welcome | D．Don’t mention it |
Doubting that the traveler carried drugs, the Customs officer stopped him and _______ his suitcase, but found nothing at all.
| A．looked up | B．went through | C．searched for | D．referred to |