三 重点句型
21. ______ the beginning of human history, people ______ at the stars and wondered what they were like. 自人类历史开端以来，人们便仰望星空，好奇它们是什么样子的。
22. They are real places like our own sun, and they are farther away than . 它们如同我们的太阳一样真实存在，而且距离远超乎任何人的想象。
23. No spacecraft has travelled another star so far. 目前没有任何航天器飞到过接近另一颗恒星的地方。
24. The man-made object which has Earth is Voyager 1. 离地球航行最远的人造物体是旅行者1号探测器。
25. The of visiting the stars gets for space flights with humans. 对于载人航天飞行来说，造访恒星的挑战更加艰巨。

21. Since; have looked up
22. anyone can imagine
23. close to
24. travelled farthest away from
25. challenge; more difficult

【解析】
21. 第一空对应“自……以来”，填Since，置于句首首字母大写；第二空“仰望”对应短语look up at，结合语境使用现在完成时，填have looked up。
22. 对应“任何人的想象”，填anyone can imagine，符合比较级后的语义要求。
23. 对应“接近”，填短语close to，符合句子语义。
24. 对应“离……航行最远”，结合现在完成时结构，填travelled farthest away from。
25. 第一空对应“挑战”，填名词challenge；第二空对应“更加艰巨”，填形容词比较级more difficult。
【答案】
21. Since; have looked up
22. anyone can imagine
23. close to
24. travelled farthest away from
25. challenge; more difficult
【知识点】
现在完成时
固定短语搭配
形容词比较级
【点评】
本题结合中文提示填写重点句型的空缺部分，既考查现在完成时、比较级等基础语法，也检验课内核心短语的识记掌握程度，属于基础的句型巩固类习题。
【难度系数】
0.7

一 用括号中所给单词的适当形式填空
1. The sports meeting (cancel) by the school because of the heavy rain yesterday.
2. The (mystery) sounds in the old forest were recorded by a team of scientists last month.
3. Scientists from different countries need to (cooperate) to solve the big problem of space travel.
4. An (man) spacecraft was sent to Mars to collect rock samples last year.
5. The train station was (crowd) with people going home for the Spring Festival.

1. was cancelled/was canceled
2. mysterious
3. cooperate
4. unmanned
5. crowded

1. 句中有时间状语yesterday，主语The sports meeting和动词cancel是被动关系，需使用一般过去时的被动语态，主语为单数，因此填对应形式。
2. 此处需要形容词修饰名词sounds，要将名词mystery变为形容词形式。
3. 固定搭配need to do sth. 意为“需要做某事”，to后接动词原形。
4. 此处修饰名词spacecraft，结合不定冠词an和“航天器被送往火星采集岩石样本”的语境，要表达“无人驾驶的”含义，用man的对应变形。
5. 固定搭配be crowded with 意为“挤满……”，需要把名词crowd变为形容词形式。