题干
The poor mother ______ and wept when she heard the news that her five-year-old son had been kidnapped.
A：broke out
B：broke dow
C：broke u
D：broke off
答案(点此获取答案解析）
B
)由两个苯环通过单键连接而成，假定二氯联苯分子中，苯环间的单键可以自由旋转，理论上由异构而形成的二氯联苯共有（ ）