(46)
A.use
B.used
C.to use
D.using

(48)
A.it
B.they
C.there
D.those

According to the passage, which of the following is the most important cause of desertification?
A.The change of climate
B.The spread of deserts
C.Human activities
D.Cattle destroying trees

When all the trees in an area are cut down, _________.
A.their leaves make the land richer
B.the smaller plants can grow better
C.they cool the land under their leaves
D.there is nothing left but sand

We can infer that men on motorcycles keep the sheep and goats away so that_________.
A.they won't eat the small trees
B.they won't destroy the covering of oil
C.they won't drink water in the canals
D.they won't blow the sand away

That's (A) the best (B) exhibition I've never (C) seen.
A.That's
B.the best
C.never
D.seen

You must take quickly (A) the test in order to (B) finish (C) in time (D) .
A.quickly
B.in order to
C.finish
D.in time

A study (A) of the (B) difference between (C) synthetic and natural vitamins are (D) needed.
A.study
B.the
C.between
D.are

He bought a ticket_________.
A.and his brother did either
B.but his brother didn't, too
C.and so his brother bought
D.and so did his brother

Don't walk too fast. I can't keep_________you.
A.on to
B.on with
C.up to
D.up with