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【单选题】
关于简谐振动的能量,下列说法正确的是A.
与振幅成正比;
B.
与频率成正比;
C.
动能和势能随时间做周期性变化;
D.
简谐振动的能量是守恒的.
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皮皮学刷刷变学霸
举一反三
【单选题】Much of the power of the trade unions has been
A.
28. Much of the power of the trade unions has beenlost , their politicalinfluence should be very great. ( 广东 ) A. As a result
B.
Asusual
C.
Evenso
D.
Sofar
【单选题】When the workers are organized in trade unions, their employers find it hard to lay them ______.
A.
out
B.
up
C.
off
D.
down
【单选题】The employers prepared, with all due ______, for a conference with the Trade Unions.
A.
caution
B.
concern
C.
certainty
D.
consideration
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