166 D.It’s a pleasure
这是一种荣幸
171 A.brought up
bring up是抚养、培育的意思
173 C.fragile
fragile 有虚弱之意
174 A.circles
circle作动词表示围绕
180 A.that
that在这里指代前面的population
182 D. knocked into
knock into是撞上的意思
197 C.has happened
do you suppose 是插入语,what has happened to him?他发生了什么事~