He tried his best to solve the problem, _______ difficult it was.
| A．whatever | B．however | C．whichever | D．wherever |
by a greater demand for green products, the food company has set higher standards to ensure the quality.
| A．Driven | B．Being driven | C．To drive | D．Having driven |
------You are lucky that she is very thoughtful and devoted to you.
------ In fact, I don’t want to ____ her with my problems all the time.
| A．hire | B．strike | C．bear | D．bother |
I had to ______ because someone else wanted to use the phone.
| A．hang on | B．keep up | C．hang up | D．ring up |
According to an old proverb，a red sky at night often fine weather the next day．
| A．indicates | B．impresses | C．obtains | D．occurs |
Most of ______ we call geniuses are successful only because they have made extraordinary efforts.
| A．which | B．that | C．whom | D．what |