All is needed is a supply of oil.
A. the thing
B. that
C. what
D. which
网友回答
A. the thing
(答案→)B. that
C. what
D. which
解析：此题all为先行词，后面that is needed为that引导的定语从句，且作从句中的主语，由于all为不定代词，此时关系词不可用which，而what不可引导定语从句；当然，若无all可选C，因为此处的All that=what…，若All the thing为先行词，后面缺乏引导定语从句的关系代词that(且在从句中作主语，不可省略)，故A后应加that。