下列关于胃癌的描述正确的是()
A.多发于60~80岁年龄组
B.女性多于男性
C.直系亲属中发病率不高
D.胃酸缺乏与胃癌有关
E.硝胺与胃癌关系不大
参考答案:D
进口、出口实验动物的检疫工作,按照《实验动物管理办法》的规定办理。
You should visit your parents _____, even when you are very busy.
A.by and by
B.more or less
C.step by step
D.now and then