In the morning, I get up _____ wash my face. [ ]
A. with
B. but
C. so
D. and
答案:D
常温下测得某气体只含碳、氧两种元素,其中所含物质均为初中化学中的常见物质.请根据有关质量比判断其组成:
(1)若m(C):m(O)=3:4,则该气体的组成物质为______;
(2)若m(C):m(O)=3:8,则该气体的组成物质为______;
(3)若3:4>m(C):m(O)>3:8,则该气体的组成物质为______.