钢筋混凝土电杆钢圈的焊口缝隙应为( )。
A．2～4mmB．2～5mmC．3～5mmD．4～6mm
参考答案：B
Smith was overweight, so the doctor urged that not only ________ have less fat and meat, but also he ________.
A．should he; take exercise
B．ought he; take exercise
C．he should; takes exercise
D．he ought; takes exercise
以下哪一项是直接内存访问（DMA）的功能？（）
A.进行数据传输时不需要CPU持续参与
B.管理存储在内存中数据的安全性
C.扩展可用内存的容量
D.存储地址帧表
