Tenses
Present perfect, a fact that is still true, "know"
I have known Katie for a year.
After the verb "found out"
I found out that he had cheated.
If, scientific fact
If water reaches 0 degrees, it freezes.
Something you can't do anymore but could do when you were a kid, "could"
In elementary school, I could run 800m without getting tired.
TENSE: Present perfect, experience, "see"
I have seen that movie.
Present perfect continuous, action still happening, "try"
I have been trying to get in to this room for an hour.
As a subject
The fact that you got 90% tells me that you worked hard.
If, possibility about weather
If the weather gets better today, I'll go for a walk.
A polite question, ask someone to do something for you, "would"
Would you mind helping me carry this box.
CLAUSE: After the adjective "worried"
I am worried that I won't pass.
Past perfect, "study"
The test was easy because I had already studied the material in Skills 300.
Defining, "book"
I have read the book that is on the shelf.
If, imagine being someone else
If I were you, I would stay home today.
A rule, "must"
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CLAUSE: Defining, unique, "only person"
She's the only person who got above 80%.
Future simple, offer help, "bring"
Don't worry, I will bring my laptop to class tomorrow so that we can work on our presentation.
Non-defining, add information about "Canada"
Canada, which is the second-biggest country in the world, is in North America.
If, imagine a different past regarding travel
If I had saved more money, I could have traveled more.
A confident guess, "must"
He's not here, so he must still be sick.
CLAUSE: Reason, "since"
Since it is a holiday, there is no class today.
Future simple, plan, "play"
I am going to play tennis this weekend.
Time, "after"
I'm going to go out after I finish my homework.
CLAUSE: Contrast, "even though"
She's in class even though she just arrived in Halifax this morning.
We don't need to say who is going to do it, "mailed"
Your new bank card will be mailed to you today.
PASSIVE: A service being done by someone else
I'm getting my painting framed tomorrow.