A complex sentence is a sentence with only one independent (super ordinate/ principle/ main) clause and one or more dependent (subordinate/ sub-) clauses.
Model sentences: As, Because, Since
The man was sent to prison as he had committed a crime.
Because the test is on Friday, you should be reading your books.
He failed in the exam since he didn't work hard.
Seeing that
Seeing that he's been off sick all week he's unlikely to come.
In case
You'd better take the keys in case I'm out.
For
I believed her for surely she would not lie to me.
After After I've spoken to them, I'll come to you.
If, Provided that, Providing that
If it rains, we will not go outside.
Provided that you have the money in your account, you can withdraw up to $100 a day.
We'll buy everything you produce, providing that of course the price is right.
As long as, So long as, Only if
We'll go as long as the weather is good.
Only if a teacher has given permission is a student allowed to leave the room.
As if, As though
He behaved as if/as though nothing had happened.
Unless
Unless you'd prefer a cold drink, have a cup of tea.
When, Once, By the time
When I was at school, I loved English.
Once you go out, take the umbrella with you.
There was no one in the room by the time I arrived there.
Whenever
Whenever you need it, you can ask for help.
Whence
They returned whence they had come.
Where
She found her purse where she had left it in the bus.
Wherever
Wherever you go, I follow you.
Whither
They did not know whither they should go.
As as
Nilar is as beautiful as her mother.
Than
Su Su is taller than Mya Mya.
So that, In order that
We took a taxi to the stadium so that we wouldn't be late for the game.
A note was sent to all the classrooms in order that every boy would know to wear a tie on Mondays.
So as to, In order to
We went early so as to get good seats.
She arrived early in order to get a good seat.
That
I think that he is honest.
Although, Even though, Though, Whereas,
Despite the fact that, In spite of the fact that, Much as
Although she is poor, she is generous.
We lost the game although/even though/though everyone played well.
Some of the studies show positive results, whereas others do not.
She was good at Physics despite the fact that she found it boring.
English became the official language for business in spite of the fact that the population was largely Chinese.
Much as I would like to stay, I really must go home.
Before, Ere
Look before you leap.
Ere they came back home, I returned.
Until, Till
Let's wait until the rain stops.
We waited till he came here.
Supposing that
Supposing that you are wrong, what will you do then?
While
Her parents died while she was still at school.
As far as
That's the truth, as far as I know it.
No sooner than
No sooner had the match started than they scored the first goal.
Whether orHe seemed undecided whether to go or stay.
Whether or not
Whether or not we're successful, we can be sure that we did our best.
Whichever
It takes three hours, whichever route you take.
Lest
He gripped his brother's arm lest he be trampled by the mob.
Except that
I didn't tell him anything except that I needed the money.
As soon as, Immediately
As soon as the train had gone, they reached the station.
Immediately she'd gone, I remembered her name.
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