若实数满足不等式组，目标函数的最大值为2，则实数a的值是
Some people believe that dreams can tell them what will happen in the future. 1 knows why this is so, but there are many stories about people. The people make their dreams 2 . One of these
In the quiet darkness, I could hear someone _______ the door and go upstairs. A. open B. to open C. opened D. to be opening
“我们是五月的花海，用青春拥抱时代……”与这首《光荣啊，中国共青团》团歌联系最密切的历史事件是 （ ） A． B．
方程组，消去后得到的方程是（ ） A、 B、 C、 D、
如图1，把一块直角三角板的直角顶点放在直尺的一边上，如果∠1=32o，那么∠2的度数是（ ）A．32o；B．58o；C．68o；D．60o．
Only after Ann read her essay the second time the spelling mistake. A. did she notice B. she notice C. does she notice D. she has n
中只有一个元素，则
( )
B．
C．
D．0或