－Have you seen the film Lost in Thailand?
－Oh, no. I ___ my homework all day yesterday.
| A．had done | B．did | C．have done | D．was doing |
We can never expect _______ bluer sky unless we create _______ less polluted world.
| A．a; a | B．a; the | C．the; a | D．the; the |
We all know that, _______, the situation will get worse.
| A．not if dealt carefully with | B．if not carefully dealt with |
| C．if dealt not carefully with | D．not if carefully dealt with |
The fearless pirates kept _______ on the waters off the coat of Somalia, from the Gulf of Aden to the Kenya border along the Indian Ocean.
| A．knocking on | B．knocking down |
| C．knocking about | D．knocking at |
_______ the pull of the earth, a rocket must reach a speed of 28440 km/h.
| A．In order to flee | B．So as to escape |
| C．To escape | D．So that to flee |
The city, _______ by an army of 1,500 soldiers, was difficult to take.
| A．protected | B．defended | C．attacked | D．prevented |