1. My sister gave me a new pair of jeans on my sixteenth birthday.
→ I was given a new pair of jeans on my sixteenth birthday by my sister.
2. He is not good at English. He can't get that job.
→ If he were good at English, he could get the job.
3. My father is a better cook than my mother.
→ My mother can't cook as well as my father.
4. Phong is the best student in our class.
→ No one in our class is better than Phong.