He likes watching his son _____ in the water. [ ]
A. swim
B. swims
C. swam
D. swimming
A
有下列九种物质,请分类:①蒸馏水 ②空气 ③液氧 ④水银 ⑤干冰 ⑥氧化镁 ⑦石灰水 ⑧红磷 ⑨高锰酸钾
(1)属于混合物的有______;(填写序号)
(2)属于单质的有______;(填写序号)
(3)属于氧化物的有______.(填写序号)
肛梳皮下有丰富的静脉丛,在病理情况下该处的静脉曲张形成内痔。()