Time Expressions
Present Perfect v.s. Past Simple
Present Perfect v.s. Present Perfect Continuous
100

We haven't done our homework.

We haven't done our homework yet.

100

... you ever ... (be) up a skyscraper? 

Have you ever been up a skyscraper?

100

It's terrible. Mary ... (have) an accident.

It's terrible. Mary has had an accident.

200

Have you visited Paris?

Have you ever visited Paris?

200

I ... (visit) it twice.

I've visited it twice.

200

You ... (play) computer games since 4 o'clock.

You've been playing computer games since 4 o'clock.

300

I've had this car ... 3 days.

I've had this car for 3 days.

300

How much ... the world population ... (increase) in the last decade?

How much has the world population increased in the last decade?

300

You are so dirty! What ... you ... (do)?

You are so dirty! What have you been doing?

400

Why is it wet here? Has it ... rained?

Why is it wet here? Has it just rained?

400

I know it ... (reach) 7 billion in 2012.

I know it reached 7 billion in 2012.

400

She ... (write) 2 excellent books.

She has written 2 excellent books.

500

I've learnt English ... I was 7 years old.

I've learnt English since I was 7 years old.

500

Where ... you ... (grow) up?

Where did you grow up?

500

My eyes hurt. I ... (work) on the computer all day.

My eyes hurt. I've been working on the computer all day.