Ⅰ. 用括号内所给单词的适当形式填空。
1. The beauty of nature is ( mystery ), so there are many things that need us to explore.
2. Our science teacher often says that ( imagine ) is the first step to great inventions.
3. In the future, people can travel to space by ( spacecraft ).
4. Several ( billion ) tons of waste are produced every year.
5. The project needs ( cooperate ) of all the members.

1. mysterious
2. imagination
3. spacecraft
4. billion
5. cooperation

【分析】本题为英语词汇适当形式填空题，解题思路为：①分析每个句子的结构，判断空格处所需的词性；②结合所给单词的词性，根据语法规则（如词性转换、数词用法、名词的用法等）变形；③验证变形后的单词是否符合句子语义和语法要求。具体到各题：1. 空格在系动词后，需形容词作表语；2. 空格在宾语从句中作主语，需名词；3. 空格在介词by后表交通工具，用原形；4. 空格前有表数量的词，billion用原形；5. 空格在动词后作宾语，需名词。
【解析】1. 句子中is为系动词，后接形容词作表语，所给词mystery是名词，其形容词形式为mysterious，故填mysterious；2. that引导的宾语从句中缺少主语，需用名词，所给词imagine是动词，其名词形式为imagination，故填imagination；3. by表示“乘坐”交通工具时，后接交通工具名词，spacecraft单复数同形，此处用原形，故填spacecraft；4. billion前有several（表数量，相当于数词），此时billion用原形，构成“数词+billion”的结构，故填billion；5. needs后缺少宾语，需用名词，所给词cooperate是动词，其名词形式为cooperation，故填cooperation。
【答案】1. mysterious；2. imagination；3. spacecraft；4. billion；5. cooperation
【知识点】英语词性转换、名词的用法、数词的用法
【点评】本题考查基础词汇的词性转换及常用语法规则，侧重学生对核心词汇变形和固定用法的掌握，属于基础题型，难度适中。
【难度系数】0.7

Ⅱ. 用方框中所给短语的适当形式填空。
on board set foot on in case
cooperate with fall asleep
1. The witness agreed the investigation.
2. Neil Armstrong was the first person to the surface of the moon.
3. The flight attendant welcomed us with a smile.
4. He packed extra batteries the flashlight stopped working.
5. He as soon as he lies down.

1. to cooperate with
2. set foot on
3. on board
4. in case
5. falls asleep

【分析】
首先明确方框内各短语的含义及用法：on board（在飞机/船等上）、set foot on（踏上）、in case（以防）、cooperate with（与……合作）、fall asleep（入睡）。接着逐个分析句子结构和语境：1. 句子含agree，需用agree to do sth结构，结合语境选cooperate with；2. 句子是the first person to do sth结构，需动词短语，选set foot on；3. 乘务员欢迎乘客的语境对应on board；4. 打包电池的目的是以防手电筒故障，选in case；5. 主语是第三人称单数he，一般现在时下fall asleep需变第三人称单数形式。
【解析】
1. 固定搭配agree to do sth，结合“证人同意与调查合作”的语境，填to cooperate with；
2. 结构the first person to do sth，结合“踏上月球表面”的语义，填动词短语原形set foot on；
3. 乘务员在飞机上欢迎乘客，填介词短语on board；
4. 打包额外电池是为了以防手电筒故障，填连词短语in case；
5. 主语he是第三人称单数，一般现在时中谓语动词用三单形式，填falls asleep。
【答案】
1. to cooperate with
2. set foot on
3. on board
4. in case
5. falls asleep
【知识点】
动词短语用法、不定式、一般现在时
【点评】
本题考查常用短语的词义辨析及语法形式的正确运用，需掌握短语含义和相关固定结构，属于基础题型。
【难度系数】
0.6

Ⅲ. 阅读短文，选择最佳选项。
Have you ever wondered what it is like to be an astronaut? They face many challenges in space. Weightlessness is bad for human health. It can cause muscle and bone loss as well as vision（视觉）problems. Cosmic radiation（宇宙辐射）can harm their DNA. So, we need to understand how the human body changes in space. But researchers don't have a good understanding of what actually
happens to DNA in space. Studying telomeres（端粒）, the “end-parts” of chromosomes（染色体）that protect the ends of DNA, may help.
Researchers know that telomeres get shorter as people get older. Stress, smoking and unhealthy environments make telomeres shorter, too. The length of telomeres is connected with the risk of heart disease and cancer. This makes them important to study for human health.
In 2015, NASA did a study on the twin astronauts Scott and Mark Kelly. Scott spent a year on the International Space Station while Mark stayed on Earth. Researchers found Scott's telomeres increased in length while in space. His telomeres then quickly shortened when he returned to Earth. In fact, they were even shorter than before he went into space. The study gave researchers valuable new information about astronauts' health. To find out if the same changes happen during a shorter trip, another study was done on four astronauts who carried out a 3-day mission. Their telomeres were longer during spaceflight. But when they returned to Earth, their telomeres shortened quickly. They slowly returned to nearly normal length about 2 months later.
Both studies showed that space trips, even short ones, can change telomere length. Scientists think telomere length changes because of cosmic radiation exposure. Radiation, which is everywhere in space, can harm DNA. Spending more time in space also means more exposure. The International Space Station has protection in areas people use often. This helps protect the astronauts from some radiation. But what if humans want to travel to or stay on other planets someday? We need a better method to reduce radiation harm.
Space is a dangerous environment.
We don't know a lot about how it can influence people's health for a long time, especially their DNA. The more we know, the better we will be able to keep our astronauts healthy. By learning more about changes like telomere length, scientists can find ways to protect future space travellers. As space tourism becomes more common, this knowledge will be key to keeping people safe and healthy in space.
1. Which problem may weightlessness bring to astronauts in space? （）
A. Cancer.
B. Bone loss.
C. Heart disease.
D. Hearing problems.
2. Why is studying telomeres important according to the text? （）
A. Because it creates a healthy environment.
B. Because it helps reduce astronauts' stress.
C. Because it protects astronauts from radiation.
D. Because it shows how DNA changes in space.
3. What can we learn from the two studies? （）
A. Scott's telomeres returned to nearly normal length finally.
B. The time of spaceflight decides telomere length changes.
C. All the astronauts' telomeres were longer during spaceflight.
D. The twin astronauts both carried out a 1-year mission in space.
4. How does the writer show the influence of space on human health? （）
A. By listing numbers.
B. By providing examples.
C. By giving instructions.
D. By introducing backgrounds.
5. What is the main purpose of this text? （）
A. To compare life on Earth and in space.
B. To share stories about famous astronauts.
C. To explain how space affects DNA and health.
D. To introduce why space tourism develops rapidly.

1－5 BDCBC

【分析】做这类阅读理解选择题，需先通读全文把握主旨，再针对每个小题的题干关键词回原文定位对应信息，对比选项排除错误表述，选出与原文一致的最佳答案。
【解析】1. 题干问失重给宇航员带来的问题，定位原文第一段“Weightlessness is bad for human health. It can cause muscle and bone loss as well as vision problems”，对应选项B（Bone loss），故选B。
2. 题干问研究端粒的重要性，定位原文第一段“researchers don't have a good understanding of what actually happens to DNA in space. Studying telomeres... may help”，结合第二段端粒与健康风险相关，对应选项D（It shows how DNA changes in space），故选D。
3. 题干问从两个研究能学到什么：A选项Scott的端粒未恢复正常（原文说回来后比之前还短），错误；B选项太空时间不决定变化（两个研究均为太空时端粒变长），错误；C选项所有宇航员太空时端粒更长（Scott和短任务宇航员均符合），正确；D选项Mark在地球，错误，故选C。
4. 题干问作者展示太空对健康影响的方式，作者举了NASA双胞胎研究、4名宇航员研究两个例子，故选B。
5. 题干问文本主旨，全文围绕太空对宇航员DNA及健康的影响展开，对应选项C，故选C。
【答案】1－5 BDCBC
【知识点】英语阅读理解（细节理解、主旨大意）、科普类阅读
【点评】本文为科普类阅读理解，围绕太空环境对宇航员健康（尤其是端粒相关的DNA变化）展开，考查学生快速定位原文信息、理解细节和主旨的能力，需准确把握原文细节，避免混淆选项。
【难度系数】0.6