低速暖机时,若真空太高,暖机时间会()
A.缩短
B.不变
C.加长
D.不一定
参考答案:C
Mr. Li asks the students in the river, because it’s too dangerous.
A.swim
B.to swim
C.not to swim
D.to not swim
物体表面或平面图形的大小叫做面积,厘米、分米、米都是面积单位.______.