Cucumber contains a high content of vitamin C which is five times higher than of watermelon.
Aones
B. it
Cthat
D. those
网友回答
A. ones
B. it
(答案→)C. that
D. those
解析：考察代词。It指代上文提到的同一事物；that指代可数名词单数或者不可数名词，后面必须有定语修饰，表示特指；one指代可数名词单数，表示泛指；ones指代可数名词复数，表示泛指。those指代可数名词复数，后面必须有定语修饰，表示特指。本题的that指代vitamin C后面有定语修饰。句意：黄瓜的维他命C含量很高，是西瓜的VC含量的五倍多。