Whether a planet can support life depends on the size and brightness of its star, that is its 'sun'. 

that is (to say)  ^{or more exactly 也就是说，确切地说（引出同位语）}

• The fare is reduced for children, that is anyone under 15 years old.
• One solution would be to change the shape of the screen, that is, to make it wider. 
• Languages are taught by the direct method, that is to say, without using the student's own language.
• I loved him ― that is, I thought I did.
• I'll meet you in the city, that is, I will if the trains are running.
• One authority on spiders made a census of the spiders in a grass field in the south of England, and he estimated that there were more than 2,250,000 in one acre, that is something like 6,000,000 spiders of different kinds on a football pitch.

i.e ^{“也就是说、即：”}

• The film is only open to adults, i.e. people over 18.
• The hotel is closed during low season, i.e. from October to March. 
• The price must be more realistic, i.e. lower.

“也就是说”

• She has worked at the bank for many years, nine to be exact. ^（后置）
• He was economical with the truth ― in other words, he was lying. 
• It's fairly risky. Or to put it another way, don't try this at home.

Imagine a star up to 20 times larger, brighter and hotter than our own sun.

Imagine ^{引导祈使句}

• Imagine life without hot water. 
• Imagine that you have just won a million pounds.
• Imagine their dismay when they found a beautifully-cooked wallet and notes turned to ash! 

up to sth. ^{含义1： as much or as many as a certain amount or number but not more 多达 …}

• The Olympic Stadium will hold up to 80,000 spectators. ^多达
• The temperature went up to 35℃. ^{上限（最高）}

up to sth. ^{含义2： = up till （时间） 英文解释：for the whole of a period until a certain time or date 直到…}

• Up to the time of his death, Richard Colson was one of the most notable figures in our town.
• Up to now, historians have assumed that calendars came into being with the advent of agriculture, for then man was faced with a real need to understand something about the seasons.

Alternatively, if the star were small, the life-supporting planet would have to have a close orbit round it and also provide the perfect conditions for life forms to develop.

alternatively ^{adv.used to introduce a suggestion or to mention sth. different to what has just been stated 或者}

• The agency will make travel arrangements for you. Alternatively, you can organize your own transport.
• We could go to the Indian restaurant, or alternatively, we could try that new Italian place. 

life-supporting ^{复合形容词}

• the planet which supports life ⇒ the life-supporting planet

复合形容词简化定语从句

• animals which eat insects ⇒ insect-eating animals 
• silverware which is made by hands ⇒ hand-made silverware
• diseases which are related to stress ⇒ stress-related diseases 
• state-owned enterprises ^国有企业
• flower-selling girls ^卖花女孩
• epoch-making masterpieces ^{划时代的作品}
• cancer-causing substances ^致癌物质

Alternatively, if the star were small, the life-supporting planet would have to have a close orbit round it and (would) also (have to) provide the perfect conditions for life forms to develop. ^{并列句的省略}

for…to do ^{引出动词不定式的逻辑主语（介词后用宾格）}

• He opened a door and stood aside for her to pass.
• Her circumstances had never been good enough for her hopes to be realized. 

But how would we find such a planet? ^{虚拟语气的省略}

But how would we find such a planet if there were such a planet? ^课文补全

At present, there is no telescope in existence that is capable of detecting the presence of life. ^{双定语修饰“telescope”}

in existence ^存在

• The organization has been in existence for 25 years. ^{介词短语做表语}
• This is the oldest Hebrew manuscript in existence. ^{这是现存最古老的希伯来语手稿。}

presence ^{n.  the existence of sb. or sth. in a particular place 存在}

• The somewhat acid flavour is caused by the presence of lactic acid. ^{略有的酸味是由乳酸的存在造成的。}
• He barely registered our presence. ^{他几乎没有注意到我们的存在。}
• The cameras were not an intrusive presence. ^{这些摄像机的存在不会造成干扰。}

The development of such a telescope will be one of the great astronomical projects of the 21st century.

develop ^{v. to design or make a new idea, product, system etc. over a period of time 开发，研制}

• Scientists are developing new drugs to treat arthritis.
• Local entrepreneurs developed fashionable restaurants, bars and discotheques in the area. ^{当地的企业家在这个地区开办了时尚的餐馆、酒吧和迪斯科舞厅。}
• He claims that several countries have developed nuclear weapons secretly. ^{他声称几个国家已经秘密开发了核武器。}

development ^{n. he process of creating a new product or method 开发，研制}

• His work is mainly in software development.
• The funds will be used for product development.
• The talks will focus on economic development of the region. ^{会谈将聚焦于该地区的经济开发。}

正规书面语中名词更正式^{(中文喜欢用动作、英文喜欢用名词)}

GRE范文

The resolution of some problems of today is urgent and critical for the survival of a society.
Overemphasis upon some existing problems could cause harmful effects.
The efforts to solve problems of the future is sometimes of paramount importance for the avoidance of potential threats or even catastrophes we can anticipate.

• His acceptance of bribes led to his arrest. 
• My arrival coincided with his departure.