V Reading: Choose the best answer for each question. Questions 21 and 22 are based on the following passage.    Nothing can be known to exist except by the help of experience. That is to say, ifwe wish to prove that something of which we have no direct experience exists, wemust have among our premises the existence of one or more things of which we havedirect experience. Our belief that the Emperor of China exists, for example, rests upontestimony, and testimony consists, in the last analysis, of sense-data seen or heard inreading or being spoken to. Rationalists believed that, from general consideration asto what must be, they could deduce the existence of this or that in the actual world. Inthis belief they seem to have been mistaken. All the knowledge that we can acquire apriori concerning existence seems to be hypothetical: it tells us that if one thing exists,another must exist, or, more generally, that if one proposition is true, another must betrue. This is exemplified by the principles we have already dealt with, such as ‘if thisis true, and this implies that, then that is true’, or ‘if this and that have been repeatedlyfound connected, they will probably be connected in the next instance in which one ofthem is found’. Thus the scope and power of a priori principles is strictly limited. Allknowledge that something exists must be in part dependent on experience. Whenanything is known immediately, its existence is known by experience alone; whenanything is proved to exist, without being known immediately, both experience and apriori principles must be required in the proof. Knowledge is called empirical when itrests wholly or partly upon experience. Thus all knowledge which asserts existence is empirical, and the only a priori knowledge concerning existence is hypothetical,giving connections among things that exist or may exist, but not giving actualexistence
21. Select the sentence that supports the author’s opinion that all a prioriprinciples are limited.
(A) Nothing can be known to exist except by the help of experience.
(B) Rationalists believed that, from general consideration as to what must be, theycould deduce the existence of this or that in the actual world.
(C) In this belief they seem to have been mistaken.
(D) Thus the scope and power of a priori principles is strictly limited.
(E) ‘if this is true, and this implies that, then that is true.’