问题
选择题
Just like fingerprints, each person’s DNA is ________unless he has a twin．
A．unusual
B．normal
C．various
D．unique
答案
答案：D
词义辨析. Unusual不同寻常的;normal普通的,一般的;various各种各样的;unique独特的,稀罕的.句意:就像指纹一样,每个人的DNA都是独特的,除非他有一个孪生兄妹.故选D.