two-word verb...

Hi,

This is the first visit.

I'd like to know two-word verb.

1) look at
2) turn off

I learned that 'at' in the first sentence is a preposition and 'off' in the second is a 'asverb'.

How can I tell a preposition from a adverb?
Best regards. :D

[Mister Micawber]

For example:

'I looked at my watch.'
'I turned off the TV.'


No rule is foolproof, but two ways are:

(1) Insert an adverb:

'I looked carefully at my watch.'
X 'I turned carefully off the TV.'

(2) Isolate the particle:

'What did you look at?'
'At my watch.'

'What did you turn off?'
X 'Off the TV.'