导体的电阻只与导体的材料有关。()
参考答案:错
I have lived in Shanghai ______.[ ]
A. for 3 years
B. since 3 years
C. 3 years ago
D. 3 years
严禁在输送机()时打炭或取杂物。
A.运转
B.停止
C.停机闭锁
D.闭锁