灭菌后的无菌包有效期为_______天。
参考答案：7
常流式动力转向器按结构布置不同有（）、半整体式和（）等。
He _____ the club and _____ its activities.
A．took part in; joined
B．joined; took part in
C．joined; took a part in
D．took part in; took part in
