.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

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

.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

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

32.So often ______ in recent years that it has almost become a rule.

_________ in recent years that it has almost become the rule．

1. A.
   So often for this to happen
2. B.
   So often is this happened
3. C.
   So often this has happened
4. D.
   So often has this happened