КАЖДОЕ ПРЕДЛОЖЕНИЕ ОБРАЗОВАТЬ В 3 УСЛОВНЫХ ТИПА
1) If you (to be) busy, I (to leave) you alone.
2) If my friend (to come) to see me, I (to be) very glad.
3) If he (to send)an e-mail, we (not toworry).

1If you are busy I'll leave you alone.If you were busy I would leave you alone.If you had been busy I would have left you alone.2If my friend comes to see me I will (shall)be very glad.If my friend came to see me I would be very glad.If my friend had come to see me I would have been very glad.3If he sends an e-mail we won't(shan't) worry.If he sent an e-mail we wouldn't worry.If he had sent an e-mail we wouldn't have worried.