题干
You won’t find paper cutting difficult _____you keep practicing it.
A：even if
B：as long as
C：as if
D：ever since
答案(点此获取答案解析）
B
You won’t find paper cutting difficult _____you keep practicing it.
A：even if
B：as long as
C：as if
D：ever since
乙醇可被强氧化剂氧化为乙酸。
可经三步反应制取
，发生反应的类型依次是