1. If only I had known about it the day before.
2. If only I had seen him once I would have recognized him.
3. If only they were not busy we would have gone to the cinema with them.
4. If only she had passed the examination she would have helped you.
5. If only we could get tickets we would have gone to Paris a week ago.
Наверно надо написать без got
1.Count to ten
2.Swing your arms
3.March if you can
4.Follow me
Для замены таких выражений : am not , is not, are not , have/has not. Универсальное сокращение, но чаще используется в разговорной и публицистической речи. Звучит красиво- [ эйнт' ].