转化中变还原过程中，维持H2O/H2的比值在（）之间，即可防止中变催化剂的过度还原。
A、1～2
B、4～7
C、8～12
D、12～15
参考答案：B
---Why are you so late?
---I was on the way when it to me that I had left my book home,so I had to fetch it.[ ]
A. occurred
B. hit
C. happened
D. reminded
