6. At present, there is no telescope in existence that is capable of detecting the presence of life.

in existence: that exists now. 现存的。如：

这张照片是那个事件的现存唯一记录。（练习（3），汉译英）

presence: being present in a place, 出席，到场，存在。如：

He is usually quite polite in my presence.

The contract was signed in the presence of two witnesses.

7. Once we detected a planet, we would have to find a way of blotting out the light from its star, so that we would be able to 'see' the planet properly and analyze its atmosphere.

blot sth out: cover or hide (writing, etc), 涂去（字迹等）；hide sth completely, 庶蔽；remove or destroy (thoughts, memories, etc) completely, 消除或抹掉（思想，记忆等）。如：

Several words in the letter had been blotted out.

A dark cloud suddenly blotted out the sun.

她尽力抹掉对那次事故的所有记忆。（练习（4），汉译英）

analyse v. 分析，分解 analysis n. 分析，分解 analytical adj. 分析的，分解的。如：

His report analyses the effect of the policy upon middle class families.

8. In the first instance, we would be looking for plant life, rather than 'little green men'.新概念英语课文下载

in the first instance: in the first place, 首先  for instance: for example. 如：

In the first instance, we had better make sure the calculations are correct.

A Frenchman, for instance, might find it hard to laugh at a Russian joke. (NCE3 Lesson29)

We hope you would meet our requirements in this instance. ( in this instance: in this case, in this situation)