第二节：语法填空（共10小题，每小题1.5分，满分15分）
Many people keep small fish as pets.   36   keep them in a tank of water, which is made of glass. People can look through it. They can see inside the tank   37 watch the fish.
The fish need room. They need oxygen to   38   (breath). There must be enough water   39  all fish. So the size of the tank is very important.
In the tank people put small plants  40  are good for fish. They give oxygen to the water. Plants help in other ways, too. They can hide among the plants and lay eggs there.
The fish must be kept in water all the time. Some can jump high.  41  the tank should be covered with enough water. This keeps the fish from   42    (jump) out.
The fish need food and should   43   (feed) every day. But  44   you give them too much food, it is very bad, for the extra food will fall to the bottom and make  45  water dirty. So the fish should get just enough food and finish it in ten minutes. Nothing should be left .