[单项选择]Three straight lines meeting at three points (constitute) a triangle.
A. center on
B. come down to
C. consist of
D. form

[单项选择]Three straight lines meeting at three points (constitute) a triangle.
A. center on
B. come down to
C. consist of
D. form

[单项选择]

Accelerated analysis approaches emphasize the construction of (71) to more rapidly identify business and user requirements for a new system. As an accelerated analysis technology, (72) reads the program code and automatically generates the equivalent system model, and the code can be obtained from (73) All system analysis approaches require some form of (74) which includes those techniques to be used to identify or extract system problems and solution requirements from user community. (75) is a classical set of techniques used to collect information about system problems, opportunities, solution requirements, and priorities.

（71）是（）
A. object models
B. prototypes
C. use cases
D. components

[简答题]　　　　　　　　　　　　　WATER The second most important constituent of the biosphere is liquid water. This can only exist in a very narrow range of temperatures, since water freezes at 0℃ and boils at 100℃. This is only a tiny range compared with the low temperatures of some other planets and the hot interior of the earth, let the temperature of the sun. 　　　　　　　　　　 (1)__________ As we know, life would only be possible on the face　　　　　　(2)__________ of a planet had temperatures somewhere within this range.　　　 (3)__________ The earth’’s supply of water probably remains quite fairly　　　 (4)__________ constant in quantity. A certain number of hydrogen atoms, which are one of the main constituents of water, are lost by escaping from the atmosphere to out space, but they are probably just about replaced by 　 　　 (5)__________ new water rising away from the depths of the earth during 　 　 (6)__________ volcanic action. The total quantity of water is not known, and it is about enough to cover