Question

He escaped by night to avoid being seen by anyone. (Use : lest...)

Answer 1

Lest is a conjunction. The most known use of lest is with ‘should’. However you can use it without should also, for example in the following sentence: He gripped his brother’s arm lest he be trampled by the mob.

The correct answer for the sentence in question is given below:

He escaped by night lest he should be seen by anyone

Or

He escaped lest he be seen by anyone.  

Answer 2

Lest being seen by anyone, he avoided it by escaping at night.

Or,

Lest he be seen by anyone, he escaped by night.

or,

He escaped by night, lest he be seen by anyone.