—What do you think has happened to Jennifer?

—I’ve no idea. ________ I haven’t heard from her yet.

A. From B. Before C. Up to now　　　　　　　 D. Long before

What do you think________ ?

1. A.
   happens
2. B.
   happening
3. C.
   has happened
4. D.
   is happened

What do you think ______?

[    ]

A. was happened   B. has happened

C. had happened   D. is happened

What do you think________ ?

[　　]

What do you think________ ?

[　　]