He never __________ to help those in trouble because he was a kind-hearted man．(   )

模仿秀，用划线词造句。

①风筝凌空飞起，渐渐高过树梢了。

②我们垂头丧气发地坐在田埂上。

③我们心中充满了憧憬和希望。

五张卡片正面分别标有 $\sqrt{2}$ 、0、tan45°、-1、 $\sqrt{6}$ ,每张卡片的背面完全相同,则随机抽两张卡片都是有理数的概率是____.

阅读理解
A
    Jennifer and William live in New York．They have a daughter, Emma，but 3-year-old Emma doesn't live with them．She is in California with her grandparents．It is Jennifer's birthday today．Jennifer and William come to a nice restaurant to celebrate (庆祝)．
Waiter：Good evening，how can I help you today?
William：We'd like a table for two, please．
Waiter：This way，please．
Jennifer：Thank you．Can we have a menu(菜单)?·
Waiter：Here you are．My name is Alan．I'm your waiter today．Would you like to hear today's specials?
William：Sure．
Waiter：Well．today's specials are chicken soup and fish and chips(炸鱼薯条)．
Jennifer：OK．I'd like fish and chips．
William：I would like to have pasta （意大利面食）with tomatoes．
Waiter：OK．Would you like to have some salad? Our salads are great．
Jennifer：I'd like a green salad．
Waiter：Very good．Would you like something to drink?
Jennifer：Oh．Water is OK．
William：I would like some orange juice，please．
Waiter：OK．So that's a green salad, fish and chips and water, pasta with tomatoes and orange juice.
Jennifer：Yes，that's right．
根据材料内容选择最佳答案。

先化简，再求值：（1﹣ $\frac{a}{a^2+a}$ ）÷ $\frac{a^2-1}{a^2+2a+1}$ ，其中a=sin30°．