已知男性蛔虫感染率高于女性，欲对比甲、乙两乡居民总的蛔虫感染率，但甲乡人口女多于男，而乙乡人口男多于女，最适当的比较方法是（）

A.分性别进行比较

B.作两乡总率比较的χ检验

C.不具可比性，不能对比

D.对性别标化后再对比两乡标化率

E.分年龄组进行比较

. Many experts agree that once these treasures are _______ to the air, great harm will be done to them. So they think it better not to unearth the treasures.

A．exposed

B．threatened

C．constructed

D．conserved