PHRASAL VERBS: LOOK

LOOK INTO: investigate.
LOOK UP TO SB.: admire.
LOOK DOWN ON SB./STH.: think that someone or something is less important than you.
LOOK BACK: to think about the past.
LOOK AROUND: to search.
LOOK AFTER: to take care of.
LOOK FOR: try to find something or someone.
LOOK FORWARD FOR STH./-ING.: to anticipate something with pleasure.
LOOK AHEAD: to think about the future.
LOOK AT: contemplate / consider.
LOOK UP: consult a reference book.

Phrasal Verbs

A phrasal verb consists of a verb and a preposition or adverb that modifies or changes the meaning; 

'give up' is a phrasal verb that means 'stop doing' something, which is very different from 'give'.  

 The word or words that modify a verb in this manner can also go under the name particle.

Phrasal verbs can be divided into groups:

Intransitive verbs
These don't take an object.
'They had an argument, but they've made up now'.
Inseparable verbs
The object must come after the particle.
'They are looking after their grandchildren.'
Separable verbs
With some separable verbs, the object must come between the verb and the particle:
'The quality of their work sets them apart from their rivals.'

With some separable verbs, the object can go before or after the particle, though when a pronoun is used it comes before the particle:
Turn the TV off.
Turn off the TV.
Turn it off.

Download a list of phrasal verbs here. 
If you are interested in doing some exercises, click here.