I think all the contractions that you have mentioned happened when they spoke and not in written English. Native speakers leave out several letters and words when they speak. This happens when you try to capture their spoken English into

I don't know. may be a thingamajig or a thingamabob!!! hahaha!

"This computer hangs often." What will be the past tense of this sentence?

He is an Indian and she is English. Why are we not using an article before 'English' if we have to use before 'Indian'?

He came when/while I was playing. Which is right? Where should I use when and where should I use while ?

I used to go there. What can be the question tag for the above mentioned statement? thanks a bunch.

I think it is an absolute adjective. you can't say more genuine or less genuine. It is like 'unique'.

What is the pattern of this sentence? He is as tall as I am. SVC " as tall as I am" is a phrase??? My friend said the first 'as' is an adverb and the second 'as' is a conjunction. I am confused. Can anyone help??

If this question comes in a grammar test, I would definitely pick 'are' but 'is' is very common in spoken English.

Collective nouns can be seen as notionally singular or plural, depending on whether one focusses on the group as a unit, or on the individual members. Americans are more likely to see "collective" nouns as single groups, and therefore use singular