It's becoming more and more of a problem worldwild

It's becoming more and more of a problem worldwide.
这成为世界越来越大的问题了!
become of = 成为
比如
The traffic in Beijing is becoming more of a challenge everyday.
再问： 不加of行不行呢？是不是因为有more才必须加of？
再答： 对， more of a 是习惯语，但口语也常说 more a challenge (of 是隐含词）。 当然你也可以说 The traffic in Beijing is becoming more challenging everyday. 异曲同工。
再问： 说到底，这里的of还是和become无关啊
再答： 对。和 become 无关。 of 是跟 more 的。