My father came back home ______I was cooking in the kitchen.
| A．at | B．but | C．in | D．while |
—I think recycling books and paper is useful．
—________
| A．I quite agree． |
| B．I have no idea． |
| C．We shouldn’t use such things． |
| D．That’s a great idea． |
—Where is David?
—I think he________Australia．
| A．has gone to |
| B．has been |
| C．has gone |
| D．has been to |
—Have you packed the camera yet?
—Yes，of course．I________it last night．
| A．have packed |
| B．was packed |
| C．packed |
| D．had packed |
Homo erectus pekinensis(北京人)________in Zhoukoudian Village，on the Longgu Mountain，Fangshan District，Beijing．
| A．has discovered |
| B．was discovered |
| C．is discovered |
| D．will discover |
Grandma________us stories when we were very young．
| A．used to tell |
| B．was used to tell |
| C．is used to tell |
| D．was used to telling |