This factory produced much dirty water, which resulted in a wide _______ of environmental problems.
| A．branch | B．range |
| C．species | D．wave |
I don’t know who invented ________ telephone. It’s really ________ most useful invention.
| A．the; a | B．/; a | C．a; the | D．/; the |
----Whose advice do you think I should take?
----________.
| A．It doesn’t matter | B．That’s it | C．It’s up to you | D．Either is OK |
I know a little bit about the city as I __________ there for one year in my youth.
| A．am studying | B．had studied | C．studied | D．have studied |
Leaves are found _______ all kinds of trees, but they differ greatly ________ size and shape.
| A．in; on | B．in; from | C．on; by | D．on; in |
To save class time, our teacher has ________ students do half of the exercises in class and complete the other half for our homework.
| A．we | B．us | C．our | D．ours |