单选题
The migratory birds use the same nests year after year,（ ）new material each time.
Aand will add
Bto add
Cwhich are added
Dadding
正确答案
答案解析
该题考查句子结构。根据句意排除B选项（不定式做状语表原因，目的或结果），选项C应为which are added by故排除，选项A不符合时态一致原则。故答案为D（分词做use伴随状语或做主语the migratory birds补足语）。