21. Unless an extension at least one week before the due date, it will not be given.
a. you request c. you requested
b. you will request d. requesting
22. The assignment made me .
a. to think hard c. think hard
b. thinking hard d. thought hard
23. The scientists were prohibited the danger zone.
a. to enter c. enter
b. entering d. from entering
24. the right answer I would have got full marks.
a. Had I known c. If I’ll know
b. if I would have known d. If I was knowing
25. The results were convincing that we decided to publish them.
a. so c. very
b. such d. so much
26. way you do it, the answer is always the same.
a. However c. Who ever
b. whichever d. Why ever
27. producing methane, the process also produces carbon monoxide.
a. Apart c. Besides
b. As well d. In addition
28. The biologist admitted excessive numbers of animals in laboratory tests.
a. using c. being used
b. to use d. used
29. A whale is a mammal, it is warm-blooded and gives milk to its young.
a. who c. which means that
b. which d. that
30. He appears minor problems.
a. to have had c. was having
b. having d. had