问题
选择题
What we want is an environmentally friendly car, especially ____ is good on gas.
A．one
B．one which
C．which
D．one that
答案
答案：D
one 作an environmentally friendly car的同位语，同时one 又是后面定语从句的先行词，定语从句中缺少主语，one 是不定代词，所以只能使用关系代词that，故选D。