泌尿、男生殖系感染的致病菌是
A．革兰阴性杆菌B．革兰阳性杆菌C．革兰阴性球菌D．革兰阳性球菌E．炭疽杆菌
参考答案：A
47. I'd like to go with you. , I have to finish the report now.
A．However
B．But
C．And
D．So
试述交流接触器的工作原理。
