A:花粉
B:酵母菌
C:纤维素
D:精子
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.
下列关于长江中下游平原自然条件叙述错误的是( )
大庆适宜发展的工业是( )