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Astronomers....(watch) the sky .... the sky ....(be) clear.
Astronomers watch the sky if the sky is clear.
.....you....(not go) outside, you... ( not see) the comet.
If you don´t go outside, you won´t see the comet.
I .... (not wait) any longer .... I .... (be) you.
I wouldn´t wait any longer if I were you.
If Ollie had saved more money, he would have be able to buy those trainers.
I ... (buy) a telescope unless it ...(cost) too much.
I will buy a telescope unless it costs too much.
If you want to be an astronomert,.....................(Physics/need/study/to/you).
If you want to be an astronomer, you need to study Physics.
............................(with us / want / if / want / wou / to / come), I´ll give you a lift.
If you want to come with us, I´ll give you a lift.
If you could go anywhere in the world, ................................(go/you/where/would)?
If you could go anywhere in the world, where would you go?
They.....(not do) the mission if they had known about the dangers.
They wouldn´t have done the mission if they had known about the dangers.
If you......(see) the film Gravity, you would have really enjoyed it.
If you had seen the film Gravity, you would have really enjoyed it.
If students fail the exam,.........................................(again / can / it / take / they).
If students fail the exam, they can take it again.
If everything goes well, we.......(reach) the space station in two days.
If everything goes well, we will reach the space station in two days.
I´d come to the party ......................................(an exam/if/tomorrow/have/I/didn´t)
I´d come to the party if I didn´t have an exam tomorrow.
If they hadn´t filmed the first landing on the moon, no one......(believe) it!
If they hadn´t filmed the first landing on the moon, no one would have belived it!
If you.......(discover) a new planet, what......you........(call) it?
If you had discovered a new planet, what would have you called it?
If you........(want) to see the stars and planets, you........(need) to have a telescope .
if you want to see the stars and planets, you need to have a telescope.
You.......(not see) the space station unless you have a good telescope.
You won´t see the space station unless you have a good telescope.
... I ...(win) the lottery, I....(buy) a ticket to Mars.
If I won the lottery, I´d buy a ticket to Mars.
We would have missed the comet if we had gone outside later.
If you.....(heat) water to 100 ºC, it boils.
If you heat water to 100 ºC, it boils.
What do people need to do if they......(want) to see the space station from Earth?
What do people need to do if they want to see the space station from Earth?
You will burn if you stay in the sun any longer.
.... you......(go) a bungee jump if your best friend ..... (ask) you to?
Would you do a bungee jump if your best friend asked you to?
Peter would have won if he........(answer) all the questions correctly.
Peter would have won if he hadn´t answered all the questions correctly.
If I......(be) a rich man, I........(buy) Venezuela.
If I were a rich man, I´ll buy Venezuela.