The professor’s research finally proved to be ______, though he had spent a lot of money on it.
| A．priceless | B．valuable | C．worthless | D．worthwhile |
The purpose of our advertising is to _________ customers’ attention to our product.
| A．pay | B．devote | C．fix | D．draw |
____ is the ability to do the job rather than where you come from or what you are that matters.
| A．It | B．That | C．This | D．There |
Parents cannot take care of them ________, so children should learn to be independent.
| A．all the time | B．at one time | C．in no time | D．at any time |
The plane lost control all of _______ sudden and crashed in________ forest 30 miles away from the Capital Airport.
| A．the, a | B．a, a | C．/, the | D．a, / |