A:淞沪会战
B:太原会战
C:武汉会战
D:徐州会战
Look, you can see many _________ in the pool. And here is some ________for you to keep them.
若a是正数,a-b的结果是( )
某人的钱包内有10元钱、20元钱和50元钱的纸币各1张,从中随机取出2张纸币.
某人站在南极点上,他的正前方是( )