The millions of calculations involved, had they been done by hand, _

单选题 The millions of calculations involved, had they been done by hand, __________ all practical value by the time they were finished.

A．had lost
B．would lose
C．would have lost
D．should have lost

参考答案C

解析:

单选题 You should have your eyes tested every year in case the __________ of your spectacles need changing.

A．lenses
B．glasses
C．sights
D．crystals

单选题 Good travelers don't leave __________ on trains or airplanes.

A．rubbish
B．litter
C．garbage
D．pollutant

单选题 The first sentence in this paragraph is __________; it can be interpreted in many ways:

A．intricate
B．ambiguous
C．duplicated
D．confused