Questions 21--25
　　In almost all cases the soft parts of fossils are gone for ever but they were fittedaround or within the hard parts. Many of them also were attached to the hard parts andusually such attachments are visible as depressed or elevated areas， ridges， or grooves，smooth or rough patches on the hard parts. The muscles most important for theactivities of the animal and most evident in the appearance of the living animal arethose attached to the hard parts and possible to reconstruct from their attachments.Much can be learned about a vanished brain from the inside of the skull in which it waslodged.
　　Restoration of the external appearance of an extinct animal has little or noscientific value. It does not even help in inferring what the activities of the livinganimal were， how fast it could run， what its food was， or such other conclusions as areimportant for the history of life. However， what most people want to know about extinctanimals is what they looked like when they were alive. Scientists also would like toknow. Things like fossil shells present no great problem as a rule， because the hard partsare external when the animal is alive and the outer appearance is actually preserved inthe fossils.
　　Animals in which the skeleton is internal present great problems of restoration，and honest restorers admit that they often have to use considerable guessing. Thegeneral shape and contours of the body are fixed by the skeleton and by musclesattached to the skeleton， but surface features， which may give the animal its reallycharacteristic look， are seldom restorable with any real probability of accuracy. Thepresent often helps to interpret the past. An extinct animal presumably looked more orless like its living relatives， if it has any. This， however， may be quite equivocal. Forexample， extinct members of the horse family are usually restored to look somewhatlike the most familiar living horses—domestic horses and their closest wild relatives.It is， however， possible and even probable that many extinct horses were striped likezebras. Others probably had patterns no longer present in any living members of thefamily. If lions and tigers were extinct they would be restored to look exactly alike.No living elephants have much hair and mammoths， which are extinct elephants，would doubtless be restored as hairless if we did not happen to know that they hadthick， woolly coats. We know this only because mammoths are so recently extinct thatprehistoric men drew pictures of them and that the hide and hair have actually beenfound in a few specimens. For older extinct animals we have no such clues.

21. According to the passage, the soft part of fossilized animals _____.
(A) can always be accurately identified
(B) have usually left some traces
(C) can usually be reconstructed
(D) have always vanished without any trace

22. The muscles of a fossilized animal can sometimes be reconstructed because _____.
(A) they were preserved with the rest of the animal
(B) they were lodged inside the animal s skull
(C) they were hardened parts of the animal s body
(D) they were attached to the animal s skeleton

23. The reconstruction of a fossilized animal s external appearance is considered necessary in order to _____.
(A) satisfy popular curiosity
(B) answer scientific questions
(C) establish its activities
(D) determine its eating habits

24. The word “equivocal” (para. 3) means _____.
(A) equally important
(B) definable
(C) equally doubtful
(D) deliberate

25. The third paragraph of the passage deals with the difficulties of restoring the following fossilized animals EXCEPT _____.
(A) those which had complex internal structures
(B) those which had no external hard parts
(C) those which had fur-covered bodies
(D) those which had no living relatives