独立避雷针是离开建筑物单独装设的,其接地装置应当单设,接地电阻一般不应超过()欧姆。
A.2
B.5
C.10
参考答案:C
阅读短文,判断短文后面的句子的正(√)误(×)。
Robot: What day is it today?
John: It's Friday. Hum.…I like Fridays.
Robot: What do you have today?
John: We have science, art and math. What about you?
Robot: We have English and P. E. What do you do on weekends?
John: I often play football.
( ) 1. It's Friday.
( ) 2. John likes Fridays.
( ) 3. John has art and P. E. on Fridays.
( ) 4. Robot has English and P. E. today.
( ) 5. John often plays baseball on weekends.
关于地球形状的说法,正确的是[ ]
A.接近正圆的球体
B.大地如覆盖
C.天圆地方
D.地方如棋局