【简答题】通常把______的透镜叫凸透镜,凸透镜对光线有______作用;把______的透镜叫凹透镜,凹透镜对光线有______作用.
【单选题】关于透镜,下列说法中正确的是( )
A.
凸透镜和凹透镜都有焦点,凸透镜有实焦点,凹透镜有虚焦点
B.
凸透镜对光有会聚作用,因此通过凸透镜的光都一定会聚在焦点
【单选题】Either your teacher or you ______ mistaken.
【简答题】Although he is o____-looking, yet he is well received by his workmates.
【单选题】Mr. Smith works with an auto company, but he _________ for this industrial exhibition, since he is on leave. [ ]
【单选题】全双工以太网传输技术的特点是()
A.
能同时发送和接收帧,不受 CSMA/CD 限制
B.
不能同时发送和接收帧,不受 CSMA/CD 限制
C.
能同时发送和接收帧,受 CSMA/CD 限制
D.
不能同时发送和接收帧,受 CSMA/CD 限制
【单选题】Either you or your teacher _________ mistaken.