108型万用表的表头用的是()。
A.磁电系
B.电磁系
C.电动系
D.液晶显示屏
参考答案:A
求倾斜角是45°,并且与原点的距离是5的直线的方程.
________they visited the Science Museum, they showed great interest in everything they saw. [ ]
A. The first time
B. For the first time
C. At first
D. At the first time