There is very simple way of measuring the height of a water-tower, which we cannot measure

There is very simple way of measuring the height of a water-tower, which we cannot measure by climbing.
Suppose, for example, that we wish to find out the height of the water-tower, AB, in a factory. We first of all go to where the water-tower is standing and measure a distance of, say, 25 feet from it. Then we take a stick, and stand it in the ground at the spot we have just marked.
Let us suppose the stick we are using is 4 feet in height. We now walk farther away from the water –tower in the same straight line as when we measured off the distance of 25 feet. We go from the water-tower until we e to point E, where with our head on the ground, we see the top of the stick and the top of the water-tower in the same height line---that is, the top of the stick just covers the highest part of the water-tower. Every schoolboy can work out the height of the water-tower now.
Suppose that the line CE is five feet. We know that the stick is 4 feet high and the distance BE is 30 feet. Thus, 5 is to 4 as 30 is to AB.
【小题1】If we want to know how high a tall tree is,    .
A. we have to climb up the tree
B. we have no way out
C. we must cut down the tree
D we needn’t climb up the tree
【小题2】 According to the passage, which of the following is correct?

【小题3】It is clear from this that the problem can be settled by     .A．a childB．the boy who has little schoolingC．everyoneD．a girl at middle school【小题4】To measure a water-tower in this way,     .A．no tool is neededB．Besides a stick, tape-measure (卷尺) or at least a ruler is necessary.C．we have to use nothing but a stick D．we have to prepare a set of expensive toolsD