电工仪表按工作原理分为()等。
A、磁电系
B、电磁系
C、电动系
D、以上都是
参考答案:D
Every year, _____ people go to visit their factory
A.a thousand of
B.thousands
C.thousand of
D.thousands of
人离地面愈高,愈不易产生恐惧心理。()