东北平原的东西两侧的山脉有()()。
参考答案:大兴安岭、长白山脉
—Are you going to help John with his Chinese this evening?
—No, He ________ to England. He will be back next month. [ ]
A. returned
B. has returned
C. returns
D. will return
对计划检修的设备,超过预安排停电时间的部分,记作()。