In a “primary succession”, what makes it possible for mosses to take root?




A.The effect of lichens.
B.The amount of sunlight.
C.The amount of moisture.
D.The type of rock.

What conditions are needed for shrubs to become established?




A.More soil must accumulate.
B.The ground must be covered with grass.
C.Smaller plants must die now.
D.Ferns must take root.

According to the passage, “streaming pupils” _____.




A.is the act of putting pupils into classes according to their academic abilities
B.aims at enriching both their knowledge and experience
C.is quite discouraging
D.will help the pupils learn best

According to the passage, which of the following is an advantage of mixed-ability teaching?




A.Formal class teaching is the important way to give the pupils essential skills such as those to be used in the library.
B.Pupils can be hindered from an all-round development.
C.Pupils as individuals always have the opportunities to work on their own.
D.A pupil can be at the bottom of a class.

________________ (53)




A.thrown away
B.torn off
C.put aside
D.recycled

A.omission
B.advertisement
C.recommendation
D.accomplishment

_________(20)




A.because
B.when
C.since
D.while

According to the passage, why were the remains of organisms trapped in swamps better preserved for the fossil record than those that were not?




A.The swamp environment reduced the amount of bacterial decay
B.Swamp waters contained higher amounts of materials such as calcium carbonate.
C.There were fewer sediments in swamps than in other bodies of water
D.Swamp vegetation accelerated the decomposition of organisms

The best fossils are those____




A.consist of Calcite and aragonite
B.from hard parts of animals or plants
C.still in the shape of the original animal or plant
D.animals or plants common for fossilization

______ (28)




A.had better
B.may
C.have to
D.should