1.The population of America is as 15 times as that of Austra

Hi
两句话都不对!
英语中倍数词的表达方法：
1．A is +倍数词+ as +adj./adv.原级+ as +B
2．A is +倍数词+ adj./adv.比较级+ than +B
3．A is +倍数词+ the+ 度量名词(size,weight,height,depth,width,length) +of +B
正确表达应该如下：
The population of America is 15 times as large as that of Australia.
The population of America is 15 times larger than that of Australia.
Tks!

第一句是对的

第二句是正确的。