________ the jewels were locked in a strong box，the thieves stole them without any difficulty.
| A．If | B．Unless | C．Although | D．Because |
But for your timely help, I ________ the project as scheduled.
| A．couldn’t complete | B．couldn’t have finished | C．can’t have finished | D．can’t finish |
That student admitted ____ in the math exam, _____ that he would never do that again in the future.
| A．to have cheated, promising | B．cheating, promised |
| C．to cheating, promised | D．having cheated, promising |
If ____ unsolved, the problem of food safety may lead to more serious results.
| A．making | B．remained | C．left | D．taking |
---Tom almost ran into a pole yesterday while driving on the highway.
--- I suppose he ____ too fast.
| A．had driven | B．was driving |
| C．must drive | D．should have driven |
Nowadays, in some western countries, coffee is ____ most popular drink, while tea comes ____ second.
| A．a; the | B．the; the | C．the; / | D．a; / |