机前冷凝器作用()
A、机前缓冲
B、除去粗VC中水分
C、除去残余的碱
D、降低粗VC温度
参考答案:B, D
如图所示的金属圆环放在匀强磁场中,将它从磁场中匀速拉出来,下列哪个说法是正确的( )
A.向左拉出和向右拉出,其感应电流方向相反
B.不管从什么方向拉出,环中的感应电流方向总是顺时针的
C.不管从什么方向拉出,环中的感应电流方向总是逆时针的
D.在此过程中感应电流大小不变
Today, under such an unfavorable social condition, many postgraduate students hardly can escape from being sidetracked by things that are irrelevant to their healthy development.
A. could hardly escape from being B. can hardly escape beingC. hardly can escape from D. can hardly be escaping