问题
单项选择题
水泵效率用（）表示
A.Q；
B.η；
C.H；
D.N。
答案
参考答案：B
搜题请搜索小程序“爱下问搜题”
水泵效率用（）表示
A.Q；
B.η；
C.H；
D.N。
参考答案：B
Mr. Black loved his daughter Helen very much. Every day he spent all of his free time 51 with her. One night, he had much work to do, 52 couldn’t play with his daughter. In order to keep her 53 , he found a map of the world in a magazine and cut it into pieces. When he 54 , Helen. camerunning to him and was ready to play. Mr. Black said he had 55 time to play fight now. He told the girl to put the pieces of paper back together to a map of the world, and then they could both play. About half an hour later, Helen came to her father and said, "Okay, it’s finished. Can we play now? " Mr. Black was surprised ~ saying, "That’s 56 Let’s go and see. " And sure enough, there was the picture of the world; all put together, every 57 in its place. Mr. Black said, "That’s surprising! 58 did you do that?" Helen said, "It was 59 . On the back of the page was a picture of a 60 .When I put the man together, the whole world fell into place. "
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