路拱
参考答案:为保证路面上的雨水及时排除,减少雨水对路面的浸湿和渗透,路面表面应做成两边低、中间高的路拱。
下列关于阿伏加德罗常数(NA)说法正确的是( )
A.乙烯和丙烯的混合物28g,含有碳原子的个数2NA
B.1摩尔氯气与足量的氢氧化钠反应,共转移了NA的电子
C.在标准状况下,22.4L的己烷,含有6NA碳原子
D.1mol/L的Na2S溶液中,含有的S2-的物质的量小于1mol
—Please read every sentence carefully. _ you are, ___ mistakes you’ll make.
—Thank you for your advice. [ ]
A. The more carefully; the fewer
B. The more careful; the less
C. The more carefully; the less
D. The more careful; the fewer