Usage of idioms and phrasal verbs?
 

Should idioms and phrasal verbs be used in an essay or in any other answer of other papers?

Is this a grave mistake or just a minor error,which can leave a bad impression?

Can they be used sparingly?

Should they be completely avoided?

Idioms in an essay
 

[QUOTE]Should idioms and phrasal verbs be used in an essay or in any other answer of other papers?
[/QUOTE]

Phrasal verbs are not as bad as idioms in terms of their usage in an essay. Avoid using idioms, as they may devalue your train of thought or the essence of paragraph if used bluntly.

[QUOTE]Is this a grave mistake or just a minor error,which can leave a bad impression?
[/QUOTE]

It depends on how and in what context you use them.

[QUOTE]Can they be used sparingly?[/QUOTE]
NEVER DO THIS, EVER! (Caps off)

[QUOTE]Should they be completely avoided?[/QUOTE]
You need not to be completely defensive or aggressive while using them. Just use one or two idioms in your whole essay only when you know they are going to fit in well. Otherwise, avoid using them. As far as Phrasal verbs are concerned, I think there are no hard and fast rules about how many you should or should not use. In fact, most of the times, Phrasal verbs help you convey your thought better compared to explaining the same thought in multiple different sentences.

Be careful about Idioms!
Phrasal verbs are NOT AT ALL harmful(:D)!

Does anyone know the difference between idiom and idiomatic expression? Are they same or different?