化合物有手性是因为分子没有______,分子实体与其镜像______重叠。
参考答案:对称性;不能。
阅读理解。
This is our classroom. It is a nice big room. The windows are big and the walls are white. There is a blackboard
on the front wall. There is a map on the back wall. It's a map of China.
Under the blackboard there is a big desk. It's for our teachers. There are fifty desks and chair in the room. They
are for us students.
What's on the teacher's desk? There are many flowers on it. They are for our English teacher. We like her. She is
a good teacher.
1. Our classroom is _______________
A. small
B. big
C. old
D. new
2. There's a ________ on the back wall.
A. clock
B. picture
C. map
D. guitar
3. There're ___________ students in our class.
A. 35
B. 40
C. 45
D. 50
4. The teachers' desk is _____ the blackboard.
A. on
B. in
C. under
D. for
5. Our English teacher is a ________
A. woman
B. man
C. boy
D. policeman
在计算一般纳税人应缴纳的增值税额时,准予从其销项税额中抵扣的是( )的进项税额。
A.购进固定资产
B.非正常损失的购进货物
C.外购货物支付的运费按折扣率计算
D.用于非应税项目的购进货物