1.choose sth.from ...从.中选择某物
2.choose 和things是被动关系关键是第二句中选C啊easy，hard 等形容词后面习惯用主动表被动的，所以就是to choose.如：He is easy to get on with.The girl is hard to please.There were so many beautiful things that it was hard to choose .中that it was hard to choose 是定语从句，可以这样来理解，To choose the things was hard .那么To choose the things是不定式做从句的主语。