The parents are their son who has been away from home for days.
A. in search of
B. to search
C. searching
D. searched for
网友回答
(答案→)A. in search of
B. to search
C. searching
D. searched for
解析：考查句子结构。句意：这对父母正在寻找他们已经离家几天的儿子。不定式表示具体的将要进行的动作，选项B不符语义。Search表示寻找某物后面一般要加介词，根据语境可知本句也不是被动语态，故用短语in search of，选A。