单选题Directions:There are 20 blanks in the following passage.
For each blank there are four choices marked A), B), C) and D) on the right side
of the paper. You should choose the ONE that best fits into the passage. Then
mark the corresponding letter on Answer Sheet 2 with a single
line through the centre. Nuclear energy is
seen as the new source of power for the future. Long ago {{U}} {{U}}
1 {{/U}} {{/U}}was thought that the atom was the smallest particle of
{{U}} {{U}} 2 {{/U}} {{/U}}. About 60 years ago, {{U}}
{{U}} 3 {{/U}} {{/U}}, scientists found that atoms of uranium, a
sort of {{U}} {{U}} 4 {{/U}} {{/U}}like coal, could be split,
and {{U}} {{U}} 5 {{/U}} {{/U}}make a lot of heat energy,
{{U}} {{U}} 6 {{/U}} {{/U}}they were hit by large numbers of
neutrons. After a lot of research, scientists found they could produce an even
{{U}} {{U}} 7 {{/U}} {{/U}}amount of heat by splitting a
{{U}} {{U}} 8 {{/U}} {{/U}}of atoms one after the other, in
{{U}} {{U}} 9 {{/U}} {{/U}}is called a chain reaction. But this
means that a lot of uranium is needed to {{U}} {{U}} 10 {{/U}}
{{/U}}the fuel to produce the heat energy and the supply will {{U}} {{U}}
11 {{/U}} {{/U}}to an end soon. Fortunately, a new development could
make uranium {{U}} {{U}} 12 {{/U}} {{/U}}in the production of
nuclear power. There are certain types of atoms, {{U}} {{U}} 13
{{/U}} {{/U}}, when they hit each other {{U}} {{U}} 14
{{/U}} {{/U}}great speed, join together {{U}} {{U}} 5 {{/U}}
{{/U}}of breaking apart, and it {{U}} {{U}} 16 {{/U}}
{{/U}}produces energy. The material needed in this {{U}} {{U}} 17
{{/U}} {{/U}}can be found in sea-water, which covers more than three-{{U}}
{{U}} 18 {{/U}} {{/U}}of the earth. Therefore, nuclear energy
produced {{U}} {{U}} 19 {{/U}} {{/U}}this way could be the
solution {{U}} {{U}} 20 {{/U}} {{/U}}the energy crisis.
单选题
A. it
B. people
C. what
D. there
【正确答案】
A
【答案解析】本题测试it先行的用法。A项中it作先行主语，原句可转换为The atom was thought to be the smallest particle，符合句意。其他选项：people根据句意后应跟主动语态，what和there均无先行用法。