1. Nobody was here on time yesterday, so the class started late.
If everybody ? (be) here on time yesterday, the class ? (not start)late
2. They may call me tomorrow, so we can play football.
If they ? (call) me tomorrow we ? (play) football.
3. They won't call me tomorrow, so we can't play football.
If they ? (call) me tomorrow, we (play) football.
4. They didn't call me yesterday, so we couldn't play football.
If they me (call) yesterday, we ? (play) football.
5. I can't buy that car, because I don't have enough money.
I ? (buy) that car if I ? (have) enough money.