It has been proved ____ several new kinds of medicine____ a positive effect on the cure of H7N9.
| A．which，has | B．if, has |
| C．that, have | D．what, have |
John may phone tonight，I don't want to go out ______ he phones.
| A．in case | B．in that case | C．so that | D．in time |
He is always helping people without expecting anything ______.
| A．in need | B．in fact | C．in danger | D．in return |
I will mark ______ everything you say.It is helpful to the English learners.
| A．up | B．down | C．out | D．off |
—Believe me，all your efforts will ______ some day.
—Thanks for your encouragement.
| A．pay back | B．pay down | C．pay off | D．pay for |
Some blood types are quite common，others are regionally______，and still others are rare everywhere.
| A．distributed | B．contributed | C．obtained | D．convinced |