41 According to the passage, a greenhouse is built to </p> A keep the plants warm. $ ~8 |5 X. g; H7 Z1 Q
B prevent air pollution.
, B0 g- V* r& x/ e5 H/ q- A C stop the greenhouse effect.
& I3 r4 ?5 _7 o" W, M: X6 \1 D D produce useful gases. 2 Q5 p! n" ~8 {" P+ K/ h+ R
42 Without the greenhouse gases, the earth would www.examw.com O( G6 o; P( b+ r+ Q0 y
A become warmer. 0 M9 S1 f: x4 w& n
B be much colder. 0 I/ _# f" _' C0 `
C move more slowly. 5 s3 e8 {& \) l+ j' K
D move quickly.
. m! C" k _( J% c 43 A major cause of the increase in the greenhouse gases is . H$ Y0 k" {. l r6 p
A the burning of trees and crops. 9 V a: k" l) z# X2 d Z
B the building of many greenhouses.
$ O, A0 G' P* D C the burning of large quantities Of coal and oil. 4 p+ {5 Y5 d; ?$ }
D the flooding of large areas of the world.
* W/ {" N T0 z- Y# r 44 According to the passage, chlorofluorocarbon gases differ from carbon dioxide in that . Y1 Y/ L% h/ E
A they are more useful.
0 X! Z+ j0 u, G* G9 I9 E B they are much heavier.
: [" {, S( z* }. n& O. e6 ~- ? C they are more efficient in making the' world colder.
9 z; o6 W! a: S* s, y- H, V D they are more effective in catching the heat from the sun. ; J, }. N2 V: _$ ^3 |/ O
45 A small increase in the earth's temperature may bring about
, g; \$ C+ ]0 p* I A a decline in agriculture. # `' _$ N& ^' G1 _; o% j, q
B a drop of the sea level. www.ExamW.CoM
# X8 j ^6 k! V C the death of all animals. % q3 B5 K) F$ u& x
D a delay in the greenhouse effect.
5 G2 X5 ~, J# R; V5 f3 I 【参考答案】 ) G6 D9 Q" g% W9 F$ {
41. A 42. B 43. C 44. D 45. A |