当先行词为all, everything, something, anything, none, little, much等或为形容词最
The little that I can do will not even be noticed.
This is the only hotel that can provide such a kind of service.
There is much that you are in a position to do.
He saw the girl，as/which he hoped.
He married her, as/which was natural.
The ships were frozen in，as/which not infrequently happens in those regions.
As was natural，he married her.(正)
Which was natural，he married her.(误)
同时，as作关系代词可用于the same ... as, such ... as, as…as等结构中。例如:
We find such machines as will best stand up to hard weather.
Such people as knew Tom admired him.
We hope the measures to control prices，as taken by the government，will succeed.
Daivd works hard，as do my brothers.
Is there anything else you'd like that you don't see on the shelves?
There was one thing he told me which I don't believe.
like的先行词是anything else，而that you don't see on the shelves in先行词则为any-
thing else you'd like.我们可再看两个例子:
Is there anything you want that you have not?
Mr. Lee is the only dealer I know who gives good prices.
They tried to think of a plan by which they could fulfil their task ahead of time.
The driver was the man from whose room she had stolen the maps.
I will now introduce the candidate in support of whom[wish to speak.
This depends on the purpose for which the exhaust steam is used. (for与purpose搭
Radial flow turbines differ in the manner in which the steam flow is arranged. (in与先
The material of which the apparatus is made is a good nonconductor of heat. (of与is
Opportunities are provided by which poor but worthy students could work out all cost
of living. (by与先行词opportunity搭配)
在prep.十关系代词前亦可加上名词或代词或其他限定词，即名词短语some , none ,
all, each, most, both, many, several等+prep.+which/whom结构。例如:
The buses，most of which are already full，were surrounded by an angry crowd.
He introduced me to his children，two of whom volunteered to go with me as a guide.
She gave me a book the title of which I've forgot.
S. prep.+关系代词+to do sth.结构
The library is a good place in which to read.
I have nothing about which to worry.
At last there was something about which to write.
Tom wants a boy with whom to play.