a) If you help me with my homework, i finish it in time to go to the cinema.

b) If it doesn't rain, the students practice sport in the playground.

c) Jane came home early if she wasn't being very busy at work.

d) Our teacher would be pleased if we did our homework.

e) If Robert plays football with us, we will win the match.

f) If we go on Holiday this Summer, we go to Spain.

g) If the weather don't improve, we can't have a picnic.

h) They would go the party if they were invited.  

i) If i don't go to bed early, I will be tired tomorrow.

2. a) If we keep polluting our planet, soon we won't have it.

b) If we use recycled paper and glass we avoid pollution in the world.

c) Children will be aware of the importance of recycling if they start learning about it from an early age.

d) If you have a shower instead of a bath you can pretend you're making a video at a waterfall and start singing.

e) If environmental issues are taught at school it can help students become aware of the planet.

4. a) Se levarmos John, ele ficará muito satisfeito.

b) Se você me der algum dinheiro, eu te pagarei amanhã.

c) Se eles nos disserem que querem, teremos que dar a eles.

d) Se Mary vier, ela vai querer dirigir.

e) Se eu for para Nova York novamente, comprarei para você uma lembrança do Empire State Building.

f) Se ele estiver se sentindo melhor, ele virá.

g) Se ela ainda não ouviu as más notícias, direi a ela.

Desculpe se algumas questões não estiverem corretas, dei meu máximo, boa sorte!