11. Not until Alexander Fleming discovered penicilline, _____ with success.
A. bacterial diseases were treated
B. the treatment of bacterial diseases done
C. doctors treated bacterial diseases
D. were bacterial diseases treated

12. Before _____ any organ transplantation, a patient must undergo a series of medical examination such as blood-matching and tissue-matching tests.
A. undergo
B. to undergo
C. undergoing
D. can undergo

13. In an X-ray, bones appear white _____ soft tissue shows up in shades of grey.
A. because
B. in spite of
C. so that
D. whereas

14. Scientists are still debating whether _____ global temperature is not just a part of the global natural cycle of climate change.
A. increasing the
B. the increase in
C. in the increase of
D. as to increase

15. There may be circumstances _____ layoffs are necessary for firms in order to survive.
A. that
B. which
C. whose
D. in which

16. Warmer seawater temperatures are causing coral bleaching, which make coral reefs more susceptible to disease and permanent loss.

= makes (singular)

17. Bacteria grow in colonies and can be reproduced quite rapid by a process called fission.

= rapidly (adverb)

18. The arguments for deep-sea exploration are similar with the reasons for sending man to the moon.

= men / a man

19. The latest clean diesel automobile, introduced at the 2010 Paris Motor Show, is expected doing quite well in European markets.

= to do (to infinitive)

20. One of the significant social phenomena of our time being the increased interest and participation of adults in educational pursuits.

= is (form of to be)