下列物质中,按单质、化合物、混合物的顺序排列的是( ) .
下列不属于西双版纳旅游名胜的是:
Microsoft ended support for Windows XP after April 8, which _______a major operating system for some Chinese computer users, and advised users to upgrade to Windows 8.1.
下列标点符号使用正确的一项是( )