请大家帮忙做一篇英语阅读,

请大家帮忙做一篇英语阅读,
Beneath the deep oceans that cover two-thirds of the Earth are concealed some of
the most tantalizing secrets of our planet.There the crust of the Earth is thinner and the
unknown mantle--the layer beneath the crust - lies closest,tempting scientists to
drill into it.The first such attempt,the ambitious Project Mohole,got under way during
the 1960's and proved the value of deep-sea drilling by making several test holes in the
mantle beneath the crust before spiraling costs led to its cancellation.
Soon afterward,however,work began on the more modest Deep Sea Drilling
Project,which is not aimed at reaching the mantle but at exploring the crust itself.This
venture uses a special ship,the Glomar Challenger,which can be held precisely in
position in the sea--without any anchor--by sound--wave guiding systems and computer-
controlled propellers.From this stable platform,scientists lowered drilling
pipes into waters four miles deep to scoop up cores of ocean sediment and bedrock.
Analysis of the fossil contents has indicated that the ocean floors spread,moving
continents around the Earth .
42.The passage mainly discusses
(A) analysis of fossils in the ocean
(B) exploration beneath the ocean bottom
(C) the composition of the Earth's crust
(D) the construction of the Glomar Challenger
43.According to the passage,one of the objectives of Project Mohole was to
(A) increase public support for underwater experimentation
(B) test the ocean bottom for unusual ocean sediment
(C) estimate the age of the Earth's crust
(D) study the Earth's mantle
44.The word "spiraling'' in ling 6 is closest in meaning to which of the following?
(A) Rising
(B) Necessary
(C) Unpredictable
(D) Circular
45.It can be infered from the passage that Project Mohole originally was intended to
(A) involve deeper drilling than the Deep Sea Drilling Project
(B) cost less than the Deep Sea Drilling Project
(C) employ fewer scientists than the Deep Sea Drilling Project
(D) yield more fossil discoveries than the Deep Sea Drilling Project
46.The expression"more modest'' in line7 is closest in meaning to
(A) more sophisticated
(B) more timid
(C) less ambitious
(D) less controversial
47.The word "precisely'' in line 9 is closest in meaning to which of the following?
(A) Exactly
(B) Clearly
(C) Economically
(D) Practically
48.According to the passage,computers are used on the Glomar Challenger in order to
(A) measure the spread of the ocean floors
(B) lower its drilling pipes into the water
(C) keep it in one place
(D) detect the location of the Earth's mantle
49.The Phrase "stable platform" in Line 11 refers to
(A) the Glomar Challenger
(B) a ship's anchor
(C) sound-wave guiding systems
(D) computer-controlled propellers
50.For which of the following terms does the author supply a definition?
(A) "mantle'' (line 3)
(B) "anchor'' (line 10)
(C) "sound-wave guiding systems'' (line 10)
(D) "bedrock''(line l2)

42.B
43.D
44.A
45.A
46.B
47.A
48.C
49.A
50.A