We can never expect_______bluer sky unless we create_______less polluted world.
| A．a; a | B．a; the | C．the; a | D．the; the |
Living in the central Australian desert has its problems, _____ getting water is not the least.
| A．for which | B．to which |
| C．of which | D．in which |
_____ could be judged from what he had said, he felt terribly sorry for what he had done.
| A．Which | B．That | C．As | D．It |
He is my father, _____ a better father does not exist.
| A．but | B．than whom |
| C．than who | D．against whom |
_____ is known to us all is that America is a developed country _____ the First World.
| A．Which; belonged to | B．As; belonged to |
| C．What; belonging to | D．It, belonging to |
The mountain-climbing ___ every one of us.
| A．has been tried | B．has tired | C．is tired | D．tired |