哪一项是早期诊断结缔组织病（CTD）重要检查（）
A.关节液检查
B.肝肾功能检查
C.血清自身抗体
D.血清补体
E.X线平片
参考答案：C
----Why does your teacher _________ play basketball?
-----Because he does not have much free time to play it.
A．never
B．always
C．usually
D．seldom
水压试验时如何防止超压？
