2.介词 + which的用法
We are not conscious of the extent to which work provides the psychological satisfaction that can make the difference between a full and an empty life.
(1)as与the same, such, so, as等关联使用。如：As the forest goes, so goes its animal life.
As is true in all institutions, juries are capable of making mistakes.
As is generally accepted, economic growth is determined by the smooth development of production.
常见的这类结构有：as has been said before, as has been mentioned above, as can be imagined, as is known to all, as has been announced, as can be seen from these figures, as might/could be expected, as is often the case, as has been pointed out, as often happens, as will be shown等。
(2)先行词是不定代词anything, nothing, little, all, everything时，关系代词用that；
(3)先行词由形容词最高级或序数词修饰或由next，last, only, very修饰时，用that；
There are few teachers but know how to use a computer.
There is no complicated problem but can be solved by a computer.