1.I don't ride the bus to school every morning because it's always so crowded (If)
=> If the bus wasn't always so crowded, I would ride it to schhol everyday.
2.The schoolchildren sowed some seeds, but they forgot to water them so they didn't grow (If)
=> If the schoolchildren had remembered to water some seeds, they would have grown.
3.Stop talking or you won't understand the lesson (If)
=> If you stop talking, you will understand the lesson.
4.The wind is blowing hard, so we won't take the boat out for a ride (If)
=> If the wind wasn't blowing hard, we would take the boat out for a ride.
5.Carol didn't answer the phone because she was studying (If)
=>If Carol had not been studying, she would have answered
6.I feel better now because you talked to me about my problems yesterday (If)
=>I wouldn't feel better now if you hadn't talked to me about my problems yesterday.
7.Because I don't have enough free time,I can't help my mother with the housework(If)
-> If I had enough free time, i could help my mother with the housework.
8.Rita is exhausted today because she didn't get any last night (If)
-> Rira wouldn't be exhausted today if she had got (some) sleep last night.
9.I didn't prepare for today's lesson: So it is difficult for me to understand the teacher's explanation (If)
-> It wouldn't be difficult for me to understand the teacher's explanation if I had prepared for today's lesson.
10 I don't want them to be upset, so I've decided not to tell them what happened.
-> They would be upset if I decided to tell them what happened.
11. Martin failed his driving test last week 'cause he was very nervous.
=> If Martin hadn't been nervous, he would have passed his driving test last week
12. Go right now or you'll be late for the train.
=> If you go right now, you won't be late for the train.
13. Sally doesn't know what she has to do for homework 'cause she was absent from school on Friday.
=> If Sally hadn't been absent from school on Friday, she would know what she has to do for homework.
14/
=> If Olga and Ivan had been paying attention, they would have sen the sign marking their exit from the....