More about Prepositions and their uses

EnglishGuru - Connectives
Good evening friends. I'm back! We've already talked about various uses of prepositions. Now let's talk about another part of speech - Conjunction. But no; let's talk about 'connectives' - which may sound unfamiliar to many. Yes, connectives are very useful to make large speeches i,e, sentences. They are also known as linking words. They are of two kinds mainly; viz, Relatives and Conjunctions. Let's discuss them one by one.
Relatives: Relatives are as follows:
Karim is the boy who came here yesterday. (who - relative pronoun)
I know Karim whose father worksin a bank. (whose - relative pronoun)
He said what I could not hear. (what - relative pronoun)
It was Rahim whose pen I borrowed. (whose - relative adjective modifying pen)
We don't go out while it rains. (while - relative adverb indicating time.)
I was watching TV when he came. (when - relative adverb indicating time)
Conjunctions: Conjunctions are chiefly of two kinds; viz, Co-ordinating and Subordinating conjunctions. Again, co-ordinating conjunctions are of four kinds. Look below:
We went there and (we) saw a tragic scene. (and -  joiner of two sentences)
He is rich but (he is) unhappy. (but - disjunctive, indicating contrast)
Read hard or/otherwise you will fail. (or/otherwise - alternative)
He studied hard so he succeeded. (so - result)

Subordinating connectives: Look below:
We failed to reach there in time as/since there was traffic jam in the road. (cause)
(Al)Though he tried his best, he could not succeed. (though - contrast)
We shall stay at home if it rains. (if - condition)
You were scolded because you made a mistake. (because - cause)
We play football till it is evening. (till - indicating time)
We played until it was dusk. (until - indicating time)
N.B.:- before, after, since, when, and while also indicate time.
That's all for now friends. We'll talk about a few more connectives next time. Feel free to ask any question. Good night and sweet dreams.