巩固性原则
参考答案：是指教学要引导学生在理解的基础上牢固地掌握知识和技能，长久地保持在记忆中，能够根据需要迅速地再现出来，以利于知识技能的运用。
-The lights were left on all night long.
-Yes. It seemed that John____.He was the last to leave. [ ]
A. was to be blamed
B. was to blame
C. had been blamed
D. should be blamed
电路如图18-3-24所示，开关S断开前电路处于稳态，t=0时，将S断开，该瞬时电感电流iL等于（）。
A.2.5mA
B.5mA
C.10mA
D.0
