下列有关郑和的说法中正确的是()
A.他共六次下西洋
B.他是太监
C.他是回族人
D.他的船队曾经到达南美洲。
参考答案:A, C
看图完成对话。
①— Can you play ____ ?
— Certainly. I can play it well.
②— Does Tom have a _____?
— Yes, he does.
③— Do you want to play _____?
— Yes, I do.
④— I don't have a _____ ?
— Don't worry.You can use mme
⑤— Hello, Peter! I have a new_____.
— Oh, It's very mce.
作为固态胶体的煤,其内部存在许多毛细管及孔隙,这些空隙的总体积占煤的整个体积的百分数叫做煤的空隙率,空隙率的计算方式为()。(DHe、DHg是用氦及汞作为置换物所测得的煤的密度)
A.空隙率=(DHe-DHg)/DHe×100%P367
B.空隙率=(DHe-DHA./DHg×100%
C.空隙率=(DHg-DHE./DHg×100%
D.空隙率=(DHg-DHE./(DHg+DHE.×100%