人本管理的概念是建立在（）.
参考答案：自我实现人的基本假设之上
It was along the Mississippi River _____ Mark Twain spent much of his childhood.
A．how
B．which
C．that
D．where
现场安全防护员与作业人员之间距离应保持在（）m范围以内，并确保对同组所有作业人员能够不间断瞭望。
A.30
B.50
C.80
D.100
