Unlike the fossil fuels of today, biofuels are renewable sources, which mean that they will not ____ easily.
| A．come out | B．break out | C．turn out | D．run out |
My mother opened the drawer to ______ the knives and spoons.
| A．put away | B．put up | C．put on | D．put together |
______ made things worse, Peter said, was that his parents stopped supporting him in developing the “flying car”.
| A．It | B．Which | C．As | D．What |
The book has been translated into thirty languages since it ______ on the market in 1973.
| A．had come | B．has come | C．came | D．comes |
There are over 58,000 rocky objects in ______ space, about 900 of which could fall down onto ______ earth.
| A．the; the | B．/; the | C．the; a | D．a; / |
--- I’m sorry. I shouldn’t have blamed you for coming back later.
--- ________. I know you were worried about me.
| A．Don’t mention it. | B．That’s all right. |
| C．You’d better not. | D．I can’t agree more. |