_________(46)
A.strict
B.severe
C.serious
D.heavy

_________(48)
A.direct
B.straight
C.immediate
D.square

_________(50)
A.circumstance
B.situation
C.case
D.form

Why do climate models need to be updated to reflect the chemistry of calcium nitrate?
A.The new particles can absorb water and retain moisture.
B.The new particles can scatter and absorb sunlight.
C.to stop acid dust
D.The new particles can absorb water, retain moisture , scatter and absorb sunlight.

Which of the following may be a result of these particles?
A.The chance of an ice age is increased.
B.We may see more rainbows.
C.The greenhouses effects are increased.
D.We may see an increase in carbon dioxide.

"The ceiling in this room doesn't look very safe, does it?" -" ________ "
A.Yes, it is
B.No, it isn't
C.No, it is going to fall down
D.Yes, it doesn't fall down

"Does your sister intend to study German?" -" __________ ."
A.Sure
B.That's a good idea
C.Yes, she intends to
D.She will

My supervisor is angry with me. I didn't do all the work that I _______ last week.
A.must have done
B.can have done
C.may have done
D.should have done

- Do you like pop music or jazz? - I don't like _______of them. I prefer classical music.
A.any
B.both
C.either
D.neither

By 1820, there were over sixty steamboats on the Mississippi river, _______ were quite luxurious.
A.which many
B.many of them
C.many of which
D.many that