超导限流器是一种短路故障电流限制装置，它由超导部件和限流电阻并联组成，原理图如图所示。当通过超导部件的电流大子其临界电流Ic时，超导部件由超导态（可认为电阻为零）转变为正常态（可认为是一个纯电阻），以此来限制电力系统的故障电流。超导部件正常态电阻R1=7.5Ω，临界电流Ic=0.6A，限流电阻R2 =15Ω，灯泡L上标有“6V 3W”，电源电动势E=7V，内阻r=2Ω，电路正常工作。若灯泡L突然发生短路，则下列说法正确的是（ ）
| A．灯泡L短路前通过R1的电流为1/3A |
| B．灯泡L短路后超导部件电阻为零 |
| C．灯泡L短路后通过R1的电流为2/3A |
| D．灯泡L短路后通过R1的电流为1A |
—The two people speak different languages and can not communicate with each other well.
—Oh，I see. That’s ________ misunderstanding occurs.
| A．when | B．what |
| C．which | D．why |
An completely new district of industry has appeared in ________ used to be wasteland.
| A．which | B．that |
| C．what | D．where |
Now _______ you have to do is to admit your mistakes and immediately correct them.
| A．that | B．whether |
| C．what | D．how |
Word came, as expected, ______ college entrance English exam will be reformed soon.
| A．it | B．what |
| C．which | D．that |
is known to all is that Beijing and Zhangjiakou have been trying to co-host the 2022 Winter Olympic Games on Nov 3, 2013.
| A．What | B．Which |
| C．It | D．As |