丁二烯的聚合是（）反应。
A.放热
B.吸热
C.不放热
D.既不吸热又不放热
参考答案：A
--How do you like these two books?
---___________ of them are interesting. I want to read them again.
A．Neither
B．None
C．Either
D．Both
要不断稳定和完善土地承包需要处理好哪几种关系？完善家庭承包经营应采取哪些措施？
