( ) 1. Who likes to sing and dance? ( ) 2. How many students are there in your class? ( ) 3. Where are you going this Sunday? ( ) 4. What time do you get up? ( ) 5. Are these stamps or pictures?
A. I'm going to the park. B. At 6: 30. C. They are pictures. D. Lily. E. Fifty-two.
2Z(g)，其中X2、Y2、Z的起始浓度分别为0.10