在一个自然生态系统中，为了利于被捕食者(如羊)种群的生存，最好将其捕食者(如狼)全部消灭。 ( )
参考答案：错
________ good use you've made of your time to study，there's still room for improvement.[ ]
A. Whatever
B. However
C. Though
D. That
胃癌最常见的好发部位是___________。
