Charles is believed_______ the floor yesterday; he is always helping others silently.
| A．to sweep | B．to have swept |
| C．having swept | D．Swept |
The theory he ____ about black hole isn’t understood by most of people.
A .put up B put down C put off D put forward
It will be many years ______ the doctors and medical scientists can find _____ for cancer.
| A．since; cures | B．when; treatments |
| C．before; cures | D．until; treaments |
The photo reminded me____ I had seen in London.
A what B .that C. of that D. of what
So amused ________ that I couldn’t help laughing when I saw the performance given by the children．
| A．I felt | B．did I feel | C．I feel | D．had I felt |
As is known to us, happiness consists ____ appreciating ____ you have.
| A．of; what | B．in; what | C．of; that | D．in; that |