特种处所内的机电设备，不暴露在外面（）水密性。
A、应保证
B、不必保证
C、可保也可不保
参考答案：A
He said he _________ his work, and then we needed to wait for him for a little while.
A．just finished
B．was just finishing
C．had just finished
D．was just finished
"竹节样脊柱"可见于下列哪些疾病（）
A.化脓性腰椎炎
B.退行性骨关节病
C.类风湿性脊柱炎
D.肥大性脊椎炎、骨桥形成
E.强直性脊柱炎
