脚手架的接头处必须在小横杆上,搭接长度应是()。
A、10-20厘米
B、20-30厘米
C、30-40厘米
D、5-10厘米
参考答案:A
下列物质中,属于非生物的是( )
A.松树
B.细菌
C.牛
D.水
The dentist _____ the man's teeth and found nothing serious with him. [ ]
A. looked after
B. looked for
C. looked over
D. looked at