9的平方根是( )。
±3
His father has worked in this factory _____ he came here in 1980.
A. since B. for C. when
明挖隧道工程中,基坑验槽的资料检查包括:测量放线记录、高程测量记录和()记录。
A.平面位置检查
B.基底高程检查
C.基坑验槽
D.基坑开挖