烃类热裂解中二次反应有哪些?
参考答案:
二次反应主要有:烯烃的裂解;烯烃的聚合、环化和缩合;烯烃的加氢和脱氢;烃分解生碳。
At the beginning of class, the noise of desks __________ could be heard outside the classroom.
A.opened and closed
B.to be opened and closed
C.being opened and closed
D.to open and close
舌红绛而光者,属()
A.阴虚
B.气虚
C.血虚
D.气阴两虚
E.水涸火炎