用氮气置换机械设备及系统中的空气,其含氧量用(),然后再通入气相液化石油气。
A.小于3%
B.小于4%
C.小于5%
D.小于2%
参考答案:A
阅读理解
My name is Frank. I am twelve. Ben is my brother. He is thirteen. We are in No.12 Middle School. My mother is a teacher. She is a Chinese teacher at our school. My father is a bus driver(司机). He is a good driver. We like our father and mother very much. I have a dog. Its name is Wangwang. It is black (黑色的). It is a nice dog. We are good friends.
根据短文内容判断正(T)误(F)。
( )1. Frank’s brother is twelve.
( )2. Frank and his brother are in the same school.
( )3. Frank’s mother is a Chinese teacher at No. 2 Middle School.
( )4. The dog isn’t black.
( )5. Frank and his dog are good friends.
从窗户射入的光的色温为()
A.3000K
B.3500K
C.5000K
D.5800K