阅读理解。
The question "How long do fish live?" is not as simple as it seems. There are thousands of different kinds
of fishes, and they are quite different from each other in size and life period. What's more, it is not easy to
find out just how long a fish lives in its natural state.
We can find out how old a fish is by studying its scales, but we can not say how long more it would have
lived if we had not caught it.
We may keep fishes and record their life period but we can't be sure that this is the length of time they
would have lived had they been left alone.
We may make marking to show how fast the fishes grow so that we can calculate the age of the largest
on record, but unless this large fish dies of old age we are still not in a position to know its natural life period.
Unlike human beings, fishes do not stop growing when they have grown up. They continue to grow as
long as they live, although the speed of growth slows down in mature fishes.
1. What can the scales of a fish tell us?[ ]
A. Its age
B. Its life period
C. Its size
D. Its growth speed
2. How can we find out the natural life period of a fish? [ ]
A. We ought to keep a fish with great care.
B. This article refers to no way of settling the problem.
C. We must go on recording while we're keeping a fish.
D. We should make marking of its growth speed and calculate its life period.
3. In the last sentence "mature fishes" refer to _____ fishes. [ ]
A. young
B. sea-water
C. fully-grown
D. fresh water
