袋鼠是比较低等的哺乳动物,表现为 [ ]
A.没有胎盘
B.前肢短小
C.有育儿袋
D.尾部粗大
答案:A
It’s his laziness that ________ his failure in the last exam.
A.resulted from
B.resulted in
C.led into
D.brought in
吸收操作的作用是分离()
A.气体混合物
B.液体均相混合物
C.互不相溶的液体混合物
D.气液混合物