家庭栽培花卉,每隔几年要重新换一次土,其原因是( )
A.花盆中的土壤被植物吸收了
B.土壤中缺少肥力及微量元素
C.土壤中植物的代谢废物太多
D.土壤中缺少有机物
答案:B
Look the dog.[ ]
A. like
B. on
C. at
D. is
12. To my surprise, some of my students_____ stay up to study for the coming examination
A.may
B.must
C.can
D.Should