问题

.So often ______ inrecent years that it has almost become a rule.

A:has this happened
B:this has happened
C:is thishappening
D:for this to happen

正确答案是：

同类题型

He will have learned English for eight years by the time hefrom the university next year

We can see lots of small islands _________the shore.

One of my teachers ____ an Englishman.

The headmaster will __________ a speech tothe visiting foreign guests this afternoon.

It’s cloudy outside Please take an umbrella —