表语是用来说明主语的身份、性质、品性、特征和状态的，表语常由名词、形容词、副词、介词短语、不定式、动词的-ing、从句来充当，它常位于系动词(be, become, appear, seem,look,sound,feel,get,smell等词)之后。表语多由形容词、名词担当，也可是介宾短语、不定式、分词或动名词等 如：
She was in hospital.
He is a doctor.
It's fantastic.
以上句子中a doctor, fantastic, in hospital就是表语
例题：
(1)
Quasars----emitting extremely intense radio waves and visible radiation.
(A) starlike objects are
(B) starlike, they are objects
(C) are starlike objects
(D) are they starlike objects
答案：C
解释：此句缺少谓语，C由系表结构组成，原句中的分词短语恰好作表语的定语。A B 与原句主语冲突，也不符合同位语的要求;D中they和starlike objects重复
(2)
Wherever there is plenty of rain during the growing season, life is ----in various forms.
(A) abundant
(B) the abundance
(C) an abundant
(D) it abundant
答案：A
解释：空格处需要is的表语，B不可数名词abundance之前不应加the;C少名词;D多代词it; A形容词，恰好作表语