2017年春节期间，开封市旅游接待总量达230.82万人次，同比增长34.5%，旅游综合收入13.91亿元，同比增长43.2%，取得了2017年全市旅游产业发展开门红，13.91亿元用科学记数法应表示为（   ）

    There is a woman ____（name）Daisy who has devoted all her life to ____（attend）to the homeless children. It's generally recognized that what she has done for children ____（deserve）to be respected by everyone. ____（personal）speaking, her selfless behavior sets a good example to us.

    There was a time when I came across Daisy who ____（invite）to deliver a speech, during which she indicated, “____（take）care of homeless children is just ____ ordinary job, but it doesn't mean that you can look down ____it. Every job is equal. We can't say which one is ____（good ）.” She also said, “Once you set out to do something, you ought to carry on with it to the end, ____ you will gain nothing in the end.”

比 大多少岁？

  ____  ____  ____ = ____ （岁）

y=$\frac{2-\cos x}{\sin x}$在点$\left(\frac{\pi }{3},\sqrt{3}\right)$处的切线与直线x+ay+1=0垂直，则a为（　　）