在压缩行程中,活塞由下止点向上止点运动,汽缸内的压力和温度同时()。
A.降低
B.升高
C.不变
D.等于大气压
参考答案:B
阅读短文,然后判断正(T)误(F)。
I have two friends. This is Sarah. She is a girl. She lives in Canada. She is 8. She is my friend. And this is
Wu Yifan. He is a boy. He is 9. He lives in China. He is my friend, too.
( ) 1. I have three friends.
( ) 2. Sarah is eight.
( ) 3. Wu Yifan is a boy.
( ) 4. Sarah lives in China.
( ) 5. Wu Yifan is ten.
北京希电公司生产的PCM复用设备进行单台测试时,在设备可用的端口连接误码测试仪,用同轴电缆直接将这台设备的()接口收发互连即可测得本台设备是否正常。
A、V.24
B、V.35
C、RS232
D、E1