说明YT-40*30各符号意义?
参考答案:
Y-单级离心油泵;T-筒型;40-单级扬程;30-级数.
选出与划线部分意思相同或相近的选项
1. How did they come here? By air.[ ]
A. By sea
B. By car
C. By plane
D. On foot.
2. Everyone is here except Danny.[ ]
A. beside
B. by
C. but
D. Only
3. The radio says the weather will be fine tomorrow. [ ]
A. that
B. it
C. the sky
D. the day
4. There is a lot of rain in summer. [ ]
A. many
B. much
C. few
D. a few
5. —I'm sorry. I'm late.
—It doesn't matter. But come to school earlier.[ ]
A. That's all right.
B. You are welcome.
C. You are wrong.
D. That's right.
A、B两城相距140千米,甲、乙两辆汽车同时从两地相向开出,1小时后相遇。已知甲、乙的速度比是3∶4,甲、乙两车每小时各行多少千米?