1. I should punish you. I shall punish you.
(Is there any difference in meaning between these two sentences?)
2. Is there a synonym of a 'police informer' that starts from an alphabet 'r'?
3. 'Come on in' was the most spoken expression I had heard in American sitcoms and movies. I don't understand why Americans use preposition 'on' before 'in'. Why don't they say 'Come in'?
« I should punish you. I shall punish you. »
The first suggests that I think that it would be a good idea that I punish you, even though I might not. The second suggests that I definitely will punish you.
"shall" (in its less complicated meaning) is used to indicate simple futurity (something that will take place) eg "I shall punish you."
"should" (amongst its meanings as the past tense of shall) can be used to express obligation or duty
eg "I should punish you." (think of this meaning as obligatory: in a moral sense, the fellow deserves to be punished).
2. 'police informer' : a word that starts with "r" [I smell a "rat"] - Houghton Mifflin eReference defines a rat (amongst its other meanings) as --A despicable person, especially one who betrays or informs upon associates--
I suppose that comes close but it doesn't give "rat" the right to be called a synonym of "police informer," "synonymous" will make more sense.
3. "Come-on in." - the same American reference (Houghton Mifflin eReference - American dictionary) defines come-on as a noun that could mean "an inducement" (you get the picture). But what do I know about American English, I'll leave that for someone else (maybe an American).
And...note, you could read volumes of books on the usage of "shall" and "should," little comments won't do much help, do a research on it.
>> 3. 'Come on in' was the most spoken expression I had heard in American sitcoms and movies. I don't understand why Americans use preposition 'on' before 'in'. Why don't they say 'Come in'?<<
It makes it sound informal, friendly, and welcoming.
Thanks for all your replies. They were a great help. Stan, you had guessed the right word for 'police informer'. It was rat. Actors in the American movie called 'reservoir dogs' were pronouncing something similar on the lines of 'rat'. It just sounded on my ears like 'red' or 'rad'. There was a d sound in the word when they were pronouncing it, otherwise I could have guessed it to some extent.