The thought of going back home was ________ kept him happy while he was working abroad．
A.that
B.all that
C.all what
D.which
网友回答
B解析句意：回家的想法是他在国外工作时唯一让他保持高兴的事情。all不定代词作表语，that引导定语从句修饰all。all that…表示“所有……的事情”。误选A项的同学要注意that作连接词的用法；C项是错误的表达方式；误选D项的同学要注意which作连接词的意义。