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搜题
【单选题】
他人在场，会影响助人行为。一般情况下，在场人数越多，助人行为（）。A.
越少
B.
越难预测
C.
越多
D.
越迅速增加
拍照语音搜题，微信中搜索"皮皮学"使用
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举一反三
【简答题】课堂讨论: 2. How can we more effectively enlarge our vocabulary?
【单选题】When scientists first warned in the 1970s that CFCs could attack ozone, the U.S. responded by banning their use in spray cans. But the rest of the world continued to use CFC - based aerosol cans, and ...
A.
Because the CFCs directly damage the people’s health.
B.
Because the CFCs are poisonous chemicals.
C.
Because the production of the CFCs costs a lot.
D.
Because the CFCs can attack ozone by liberating atoms of chlorine.
【单选题】Electricity is used ___________heating and lighting and it is also used _________provide power ___________ machines.
A.
for, to, for
B.
for, for, for
C.
to, to, to
D.
to, to, with