`86.` It’s a great idea for you to take part in the summer camp in Canada. (were)
`=>` If I were you, I would take part in the summer camp in Canada.
`87.` We haven’t seen Barak for more than six months. (last)
`=>` We last saw Barak more than six months ago.
`88.` It’s three years since I started learning Spanish. (for)
`=>` I have learned Spanish for three years.
`89.` They gave my village a ton of rice three days after the earthquake. (was)
`=>` A ton of rice was given to my village three days after the earthquake.
`90.` They believe he is the richest man in the world. (to be)
`=>` He is believed to be the richest man in the world.
`91.` I’ll be back tomorrow if the weather is good. (unless)
`=>` I’ll be back tomorrow unless the weather is good.