图形所表示的各个部分不在同一个平面内,这样的图形称为______图形.
图形所表示的各个部分不在同一个平面内,这样的图形称为立体图形.
故答案为:立体.
—I saw Helen in the library this morning.
—No, it ______ her. She moved to France last week. [ ]
A. can't be
B. can be
C. mustn't be
什么是脉冲频率?