Rewrite these sentences using impersonal passive structures.
1.Linguists expect that by 2050 7,000 languages will disappear.
2.Nutritionists say that kale is the most nutrient-dense food there is.
3.Palaeontologists think there were over 500 different species of dinosaur.
4.Experts believe that 1.24 million people were killed in road traffic accidents in 2010.
5.We now know that cats are able to produce about ninety different sounds more than dogs.