Prospect for/of - should not lock this door

[salvador.dal1950]

Hello. I've two quick questions.

When should I use "prospect for" and "prospect of".

For example:

• prospect for: The prospects for employment in the technology sector are especially good right now.
• prospect of: Doctors say there is little prospect of any improvement in his condition.

The second question.

Under no circumstances should this door be locked.
Under no circumstances this door should be locked.

Looking at the solution of the exercise, I realize that the second one is wrong. Why?

Thank you !

 

[MikeNewYork]

Hello. I've two quick questions.

When should I use "prospect for" and "prospect of".

For example:

• prospect for: The prospects for employment in the technology sector are especially good right now.
• prospect of: Doctors say there is little prospect of any improvement in his condition.

The second question.

Under no circumstances should this door be locked.
Under no circumstances this door should be locked.

Looking at the solution of the exercise, I realize that the second one is wrong. Why?

Thank you !

I don't think I can answer your first question. In many cases, either preposition could be used. Your second sentence, for example could also be "little prospect for". Preposition choice is often idiomatic.

In your second question, when a negative adverbial phrase begins a sentence, we invert the subject and verb. Why? I haven't a clue.