下列对某地等高线地形图的分析中，说法正确的是（　　）

若集合$A=\left\{x\right|x^2-9x<0,x\in N*\},B=\{y|\frac{4}{y}\in N*\},$则$A\cap B$中元素个数为 （   ）

请根据句意从方框中选择合适的单词，并用其适当形式填空，使句子通顺。

(1)In the modern world, we should pay more attention to food. We should eat very ____ .
(2)Today is Children's Day. The children are enjoying ____ festival now.
(3)To support a big family, his father has to look for a ____  job besides delivering newspapers and milk.
(4)For your____ , you mustn't stand under the tree when it's raining in summer.
(5) Last month, Mrs Obama, U.S. First Lady, paid a week-long visit to China focusing on ____. She visited some schools and universities.