解题时要遵循下列原则：1.判别是不是定语从句；
2.如果从句中缺少主语、表语、宾语，就要用关系代词来引导从句；
3.如果从句中缺少状语，就得用关系副词来引导从句；
4.判断先行词的确切含义，再确定选用关系词。
①Ted came for the weekend wearing only some shorts and a T-shirt, ________is a stupid thing to do in such
weather.
A. this B. that C. what D. which
②Whatever is left over may be put into the refrigerator, ________ it will keep for two or three weeks.
A. when B. which C. where D. while
③Between the two parts of the concert is an interval, _______ the audience can buy ice-crea
