题目内容
32.So often ______ in recent years that it has almost become a rule.
| A.has this happened | B.this has happened |
| C.is this happening | D.for this to happen |
A
略
练习册系列答案
相关题目
题目内容
| A.has this happened | B.this has happened |
| C.is this happening | D.for this to happen |