[单项选择]　　　 Under the Earth’’s topsoil, at various levels, sometimes under a layer of rock, there am 　　　 deposits of clay. Look at cuts where highways have been built to see exposed clay beds; or 　　　 look at a construction site, where pockets of clay may be exposed. Rivers also reveal clay along their banks, and erosion on a hillside may make clay easily accessible. (5)　 What is clay made oF The Earth’’s surface is basically rock, and it is this rock that 　　　 gradually decomposes into clay. Rain, streams, alternating freezing and thawing, roots of 　　　 trees and plants forcing their way into cracks, earthquakes, volcanic action, and glaciers-all 　　　 of these forces slowly break down the Earth’’s exposed rocky crust into smaller and smaller 　　　 pieces that eventually become clay. (10)　 Rocks are composed of elements and compounds of elements. Feldspar, which is the 　　　 most abundant mineral on the Earth’’s surface, is basically made up of the oxides silica and 　　
A. buried
B. improved
C. available
D. workable

[单项选择]　　　 Under the Earth’’s topsoil, at various levels, sometimes under a layer of rock, there am 　　　 deposits of clay. Look at cuts where highways have been built to see exposed clay beds; or 　　　 look at a construction site, where pockets of clay may be exposed. Rivers also reveal clay along their banks, and erosion on a hillside may make clay easily accessible. (5)　 What is clay made oF The Earth’’s surface is basically rock, and it is this rock that 　　　 gradually decomposes into clay. Rain, streams, alternating freezing and thawing, roots of 　　　 trees and plants forcing their way into cracks, earthquakes, volcanic action, and glaciers-all 　　　 of these forces slowly break down the Earth’’s exposed rocky crust into smaller and smaller 　　　 pieces that eventually become clay. (10)　 Rocks are composed of elements and compounds of elements. Feldspar, which is the 　　　 most abundant mineral on the Earth’’s surface, is basically made up of the oxides silica and 　　
A. conceal layers of rock
B. can be found in various places
C. are usually small
D. must be removed from construction sites

[填空题]Without the sun’s light (warm)______ the earth’s surface, it would be so cold that life could not exist on the earth.

[单项选择]（）energy under the earth must be released in one form or another, for example, an earthquake.
A. Accumulated
B. Gathered
C. Assembled
D. Collected

[填空题]S3. If the temperature at the earth’s surface is 20F, the temperature in a coal mine 500 feet below the surface would be _____________________.

[简答题]Most geologists believe that the earth’s primordial ocean was made of ______ from volcanic eruptions.

[单项选择]Scientists generally agree that the earth’s climate will warm up over the next 50 to 100 years ______ it has warmed in the 20000 years since the Ice Age.
A. as long as
B. as much as
C. as soon as
D. as well as

[单项选择]Scientists generally agree that the Earth’s climate will warm up over the next 50 to 100 years ______it has warmed in the 20,000 years since the Ice Age.
A. as long as
B. as much as
C. as soon as
D. as well as

[单项选择]Passage Five