题目

Babar Ali is a 16–year–old boy from India. He is _______ at his lessons (功课) at school. He wants to _______ the other children（孩子们）in his village（村庄）. They are very poor (贫穷). They _______ go to school. Every day, Ali runs home _______ school. Hundreds of children are in his backyard（后院）. They _______ Ali to teach them. They love him and thank him a lot _______ his help. Ali is glad to help them. He thinks they are his brothers and _______, and he is happy for his big _______.In fact, he began (开始) to teach his friends when he was nine years old. He ha用4、7、9和六个0这九个数字按要求写出九位数．（1）约等于5亿的数是______　（2）在7亿和8亿之间的数是______（3）约等于10亿的数是______　（4）能写出小于4亿的数吗？______．