preposition

[Wong]

Hi teachers and wise ones,
a)I've seen the following sentences while surfing the net and i'm confused.Which preposition is correct? "in" or "on" someone's lap?
1-the child sat in her lap.
2-the child sat on her lap.

b)Why is the word "impersonating" uses no preposition while "masquerade" and "disguise" always uses the preposition (as)? and also,what are the differences among these three words?Can they all just be interchanged?
1-He disguised himself as a policeman.
2-He impersonated a policeman.
3-She was masquerading as a respectable businesswoman.

thanks a lot for this great site.

[Wanderer]

I think on is the correct preposition. About the three words, requiring a preposition or not depends on its own characteristics.
_________________
Let my English be checked!

[Jamie (K)]

Question a)
Both "in" and "on" are correct.
And don't ask me now what the difference between them is. It's so small that it's not even important.

Question b)
"Impersonate" involves behavior.
"Disguise" and "masquerade" involve putting on clothing.

[Wanderer]

And what about camouflage?
_________________
Let my English be checked!

[Wong]

Thanks a lot jamie(k),your explaination is very clear and simple.Now my mind is cleared..By the way, there was a typo error on sentence 2b.......he impersonated policeman(witout an 'a').

[Beeesneees]

[Wong]

Hi jamie, i realised i made a spelling mistake.'explaination' should actually be "explanation'.For example: I explained, my explanation , i'm explaining.Am i correct?.