_____ worries me is _____ we’re going to pay for all this.
| A．It, that | B．That, how |
| C．What, how | D．As, that |
The house _________ now used to be a storeroom.
| A．to be torn open. | B．torn down | C．being torn down | D．tearing open |
The boy kepthis mother for more chocolate，and finally his mother．
| A．asking for；gave away | B．asking；gave up |
| C．asking；gave in | D．asking for；gave off |
____ a computer works is a question ___ not everyone cad answer quickly.
| A．That；which | B．How；that | C．What；which | D．When；that |
All passengers ______ are expected to fasten the seat belts when the plane takes off and lands．
| A．on aboard | B．on board | C．on the board | D．on boards |
Yellow Stone National Park, ________in 1872, _________over three million visitors every year, is America’s first and foremost National Park．
| A．establishing, attracted | B．having established, attracted |
| C．established, attracting | D．being established, attracting |