高频系统中，晶体管对电磁场干扰很敏感，一般都应作电磁屏蔽。
参考答案：对
—When do you ______?
—We usually have ______ Tuesday. [ ]
A. have PE, in
B. have PE, on
C. have the PE, in
D. have the PE, on
化脓性关节炎的感染途径为（）.
A.血源性
B.关节开放性创伤
C.创口感染
D.邻近软组织感染
E.骨髓炎
