____under the tree was a charming girl aged about seventeen or eighteen.
| A．Sat | B．Sitting | C．To sit | D．Sit |
I just wonder ________ that makes him so excited．
| A．why it does | B．what he does | C．how it is | D．what it is |
A new college is being built in ________ I can remember was an old factory 20 years ago．
| A．which | B．where | C．that | D．what |
A clean environment can help the city bid for the Olympics, which ________ will promote its economic development．
| A．in nature | B．in return | C．in turn | D．in fact |
Letterboxes are much more ________ in the UK than in the US, where most people have a mailbox instead．
| A．common | B．normal | C．ordinary | D．usual |
I’d appreciate _________ if you would like to teach me how to use the computer．
| A．that | B．it | C．this | D．you |