Reading is not the only way to gain knowledge of the work in the past. There is another la
Another source of knowledge is the vast store of traditional practices handed down from father to son, or mother to daughter, of old country customs, of folklore (风俗). All this is very difficult for a college student to examine, for much knowledge and personal experience is needed here to separate good plants from wild grass. The college students should learn to realize and remember how much of real value science has found in this wide and confused wilderness and how long scientific discoveries of what had existed in this area long.
In the last paragraph the phrase "this wide and confused wilderness" refers to ______.
A.personal experience
B.wild weeds among good plants
C.the information from the parents
D.the vast store of traditional practices