Recently scientists 1(found out, has found out, find out, have found out) more about life on planet Earth and now they 2(knew,have known, know, known) better where to look for life in outer space. For a long time, scientists 3(believe, believed, believes, have believed) that life 4(depended,depend,depends,have depended) on sunlight for energy. Then, in 1978,a submarine 5(dive,have dived, has dived, dived) to the bottom of the Pacific Ocean. Although there 6(were, was, has been, have been) no sunlight, and they 7(have found, finds, found, has found) tube worms, clams and crabs, and other life forms.
2.This monkey is the most unhappy in this Zoo!
3.I have written the shortest book in my life.
4.Mr.Brown is taller than Mr.Smith.
5.The weather is finer today than it was yesterday.
6.Tom is the cleverest manager in our company.
7.It was a wonderful day!
8.Today the film was more interesting than it was yesterday.
9.The tea is too hot.Make it colder!
10.Your sister is taller than you.
11.This puppy is the cleverest! I'll take him!