单相短路只可能在（）中发生。
A、中性点不接地系统
B、中性点接地系统
C、小电流接地系统
参考答案：B
China’s youths topped a list of calculating abilities, but ranked last on ________imagination and 5th from ________ bottom for creativity, according to an educationsurvey of 21 countries and regions.
A．the, the
B．an, the
C．/, the
D．/ a
减少Cache失效开销有哪些方法？
