单选题 {{B}}Directions:{{/B}} Read the following text. Choose the best word(s) for
each numbered blank and mark A, B, C or D on ANSWER SHEET 1.
Researchers have found that migrating
animals use a variety of inner compasses to help them navigate. Some{{U}}
(1) {{/U}}by the position of the Sun. Others navigate by the stars.
Some use the Sun as{{U}} (2) {{/U}}guide during the day, and then{{U}}
(3) {{/U}}to star navigation by night. One study shows that the
homing pigeon uses the Earth's magnetic fields as a guide{{U}} (4)
{{/U}}finding its way home, and there are indications that various other
animals, from insects to mollusks (软体动物), can also make{{U}} (5)
{{/U}}of magnetic compasses.{{U}} (6) {{/U}}is of course very
useful for a migrating bird to be able to switch to magnetic compass when clouds
cover the sun;{{U}} (7) {{/U}}it Would just have to land and wait for
the Sun to come out again.{{U}} (8) {{/U}}with the Sun or stars to steer
by, the problems of navigation are more complicated{{U}} (9)
{{/U}}they might seem at first. For example, a worker honeybee{{U}} (10)
{{/U}}has found a rich source of nectar and pollen flies rapidly home to the
hive to{{U}} (11) {{/U}}: A naturalist has discovered that the bee
scout{{U}} (12) {{/U}}her report through complicated dance in the
hive,{{U}} (13) {{/U}}she tells the other workers not only how far away
the food is, but also what direction to fly in{{U}} (14) {{/U}}to the
Sun.{{U}} (15) {{/U}}the Sun does not stay in one place all day. As the
workers start{{U}} (16) {{/U}}to gather the food, the Sun may{{U}}
(17) {{/U}}have changed its position in the sky somewhat. In later
trips during the day, the Sun seems to move farther and farther toward the west.
Yet the worker bees seem to have no{{U}} (18) {{/U}}at all in finding
the food source. Their inner{{U}} (19) {{/U}}tell them just where the
Sun will be, and they change their course{{U}} (20)
{{/U}}.
【答案解析】本句的意思是说白天动物靠太阳辨别方向，到了晚上就靠星星导航(star navigation)，此处的动词表示转向的意思，因此首先应该排除plunge(投入，陷入)，revolve (围绕……旋转)。选项convert一般表示宗教信仰的改变，只有switch(转换)符合题意。这在本段末也可以找到印证。switch还常常表示语言的转换，如；He switched to English when he spoke to his girl friend．(他对女朋友说话时，改说英语了。)
【正确答案】
A
【答案解析】in doing something表示在做什么事情的时候，如：In crossing the street he was run over．(过街时，他被撞了)。因此in正确，表示动物回家靠的是地球磁场的指示。
【正确答案】
C
【答案解析】本题中只有选项use可以与句中的make组成make use of(利用)的搭配，其他词都不正确。
【正确答案】
D
【答案解析】本句是对句子结构的考查，即句型“It+be+adj．+to do something”，因此只能选择It，其余选项都不合语法要求。