这句话的语法错误该怎么改?

题目

这句话的语法错误该怎么改?
What’s more, the babyboom appeared in 2010, the newborns in Beijingand Shanghaihave reached 10 million, and such a huge market was an opportunity forinternational brand of milk powder.

答案

建议在2010 后面加一个when,然后把从句中的时态改成过去时：
What’s more,the babyboom appeared in 2010 when the newborns in Beijingand Shanghai reached 10 million,and such a huge market was an opportunity forinternational brand of milk powder.