.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.