皮皮学，免费搜题
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搜题
【判断题】
合外力为零,内力只有保守力的系统,机械能必然守恒。A.
正确
B.
错误
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参考解析：
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举一反三
【判断题】The initial letter does not refer to the letter of establishing business relations.
A.
正确
B.
错误
【单选题】The letter ______ three days ago and it ______ yesterday. [ ]
A.
had post, had arrived
B.
was posted, arrived
C.
posted, arrived
D.
had been posted, was arrived
【单选题】The use of standard components makes ()easier when they are worn.
A.
replacement
B.
place
C.
repair
D.
modification
【判断题】The initial letter does not refer to the letter of establishing business relations.
A.
正确
B.
错误
【单选题】Franklin compared himself to a worn-out carpet in order to show that he was too exhausted to be of any use to his country.
A.
Y
B.
N
C.
NG
相关题目：
【判断题】The initial letter does not refer to the letter of establishing business relations.
A.
正确
B.
错误