临时用电许可证的有效期为（）
A.1周
B.1月
C.一个班次
D.15天
参考答案：A
Unless ________ to speak,you should remain silent at the conference. [ ]
A. invited
B. inviting
C. being invited
D. having invited
哪种肺炎最易并发肺脓肿（）
A.肺炎球菌肺炎
B.支原体肺炎
C.葡萄球菌肺炎
D.克雷伯杆菌肺炎
E.病毒性肺炎
