课后练习：

1 Rock and soil samples and information of many otherkinds have become ______ in recent years.

A accountable Bconsiderable C available D possible

2 Many felt______ the astronauts could bring back toearth some strange infection.

A it was achance that Bthere was a chance that

C it is a chancethat D there is a chance that

3 Like the earth，the moon is in ______, with a crust on the outside and adeep mantle below.

A liars B layers C lava D lead

4 It has the same chemical elements­­­ _____ have theearth and the rest of the solar system but in very different ______.

A that,amounts B which, numbers C as, amounts D that, numbers

5 The surface itself ranges from heat of 230F to cold of _____ 290F, depending upon where the sun is.

A plus B minus C major D minor

6 The moon was born someplace else in the solar systemand then _____ by the earth’s gravity.

A captained B capitalized C captured D capped

7 _____ all we have learned from space flights ， the moon is stilla riddle from the distance past.

A Despiteof B Despited C In spite D In spite of

答案：1C 2B 3B 4C 5 B 6 C 7D