Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 21 to 25. There are 4400 living species of amphibians. Frogs, toads, newts and salamanders are all amphibians. Many live mainly on land, but most spend at least some of their lives in water. The largest amphibian, the Chinese giant salamander, is 1.8m long. Frogs and salamanders are able to breathe through their damp skins to a certain extent, both in the water and on the land, but toads rely largely on their lungs and cannot remain underwater for long. Toads and frogs are similar in many ways, although toads usually have rougher, drier skins and may waddle rather than hop as frogs do. Some toads produce spawn in strings like necklaces, rather than the mass of eggs laid by frogs. Most amphibians lay their eggs in water. Frogs’ eggs are called spawn. The eggs are protected from predators by a thick layer of jelly. A tadpole develops inside each egg. When it hatches, it is able to swim using its long tail, and it breathes through gills. As a tadpole grows, first hind legs then forelegs begin to form. Lungs develop, and the young frog is able to begin to breathe with its head above water. Gradually, the tail shortens until the young frog resembles its adult parents. 21 .The text describes amphibians as animals that ________. A. do not have lungs B. can live on land and in water C. use their gills to eat and breathe D. cannot swim very well 22. According to the text, the world’s largest amphibian is a ________. A. frog B. toad C. newt D. salamander 23. One of the differences between frogs and toads is that ________. A. frogs have drier skins B. frogs develop tails as adults C. frogs can stay underwater longer D. frogs lay eggs in strings 24. Young frogs start to breathe with their heads above water when they ________. A. develop lungs B. develop internal gills C. hatch out of their eggs D. start eating insects 25. The underlined word "predators" in the passage probably means ________. A. animals that eat other animals B. animals that feed on grass C. amphibians living in water D. amphibians living on land