直线  $\left\{\begin{array}{c}x=1-\frac{1}{2}t\\ y=-3\sqrt{3}+\frac{\sqrt{3}}{2}t\end{array}\right.$（t为参数）和圆x² +y²=16 交于A，B  两点，则 AB 的中点坐标为（    ）

马云曾说过：“碰到一个强大的对手的时候，你应该做的不是去挑战它，而是去弥补它。”这句话旨在说明（　）

下列不属于生物基本特征的是（  ）

请根据要求改写下列句子，每空一词。
____ Susan has a good time on her birthday every year. (改为否定句)
Susan    ▲       ▲   a good time on her birthday every year.
____ Xiao Li paid more than 4,000 yuan for his new iPhone 4? (对划线部分提问)
   ▲       ▲   did Xiao Li pay for his new iPhone4?
____ The manager told them to be more creative in their work. (改为被动语态)
They    ▲       ▲   to be more creative in their work.
____ Some children are so young that they can’t tell the bad from the good. (保持句意基本不变)
Some children aren’t     ▲       ▲   to tell the bad from the good.
____ Rose went to the car exhibition yesterday. Danny went there, too. (保持句意基本不变)
  ▲   Rose    ▲   Danny went to the car exhibition yesterday.