（）simplicity, we may put the theory briefly as follows.

单项选择题All units of measurement are（）, because space, time, weight, and other dimensions are not naturally divided into units.

A.objective
B.traditional
C.artificial
D.controversial

单项选择题Some creatures, for example, lizards (蜥蜴), can（）lost parts of their bodies, but we human beings can not.

A.produce
B.reproduce
C.recover
D.cultivate

单项选择题I didn't expect that he would take（）of my failure to achieve his own goal.

A.chance
B.effect
C.occasion
D.advantage

单项选择题The pioneers（）their journey after a short rest.

A.assumed
B.presumed
C.resumed
D.consumed

单项选择题When she retired she did a lot of（）work for the Red Cross.

A.valid
B.portable
C.prosperous
D.voluntary

单项选择题What these young men were doing（）a threat to the safety of the whole neighborhood.

A.constructed
B.contracted
C.constituted
D.contributed

单项选择题Doctors hope to（）a human heart into the patient within the next few days.

A.transfer
B.transform
C.transplant
D.transport

单项选择题The tension（）as the guest of honor was about to announce the winner.

A.mounted
B.accented
C.climbed
D.raised

单项选择题How to dispose （） the nuclear waste is a pressing problem for scientists and politicians alike.

A.of
B.with
C.through
D.behind

单项选择题Harry（）his pants at the seams (接缝) when he bent over.

A.sliced
B.split
C.cracked
D.broke