Correct form of the verbs

When we arrived at the restaurant, the chef (a)   (already/ prepare) our table.

By the time I got home, my roommate (a)   (finish) all the pizza.

My grandma (a)   (often/ cook) traditional meals from her home country.

If I (a)   (know) how to make sushi, I would eat it every day.

Last summer, we (a)   (visit) three countries in Europe.

If you (a)   (not book) your flight soon, the price will go up.

Astronauts (a)   (conduct) numerous experiments on the International Space Station since it was launched in 1998.

I (a)   (study) English for five years and I still make mistakes.

A new satellite (a)   (launch) by NASA last month.

If you (a)   (practise) every day, you will get better at speaking English.