如果需要重复执行某个命令，可以（）。
A、按空格键
B、按中键
C、按Enter键
D、按左键
参考答案：A, C
The Arctic is considered _____ the northern part of the Atlantic.
A．having been
B．to have been
C．to be
D．being
4KW追光灯泡的正极在哪边？
