气泡吸收管使用前要进行吸收效率实验,要求1个管的采样效率达到()
A.80%以上
B.75%以上
C.85%以上
D.70%以上
E.90%以上
参考答案:E
根据短文内容回答问题。
Dear Amy,
How are you ? My name is David. I'm an American boy. For me, sports are fun. I have a collection
of sports things. I have six basketballs , three tennis rackets, nine volleyballs, four soccer balls, and five
baseballs. I play sports and I watch them on TV. Do you play sports?Do you have a sports collection?
1. Is David American?
_____ , _____
2. Are sports fun for David?
3. Does David have a collection of sports things?
4. How many baseballs does he have?
_______________________.
5. Where does David watch sports ?
各国财政收入最重要的收入形式和最主要的收入来源是( )。
A.国债收入
B.国有资产收益
C.收费收入
D.税收