focus on obstacle to doing为什么用动名词

问题描述

In this paragraph, the speaker focuses on the first obstacle to becoming a professional writer.
请问为什么是 to becoming？可以改成 to become 吗？改了之后有什么不同？

老师答疑

陈老师：

▲同意 zhouxiao5227老师的看法，该用法与名词 obstacle 的搭配有关！名词obstacle 后面通常接介词 to 表示“……的障碍”。由于这里的 to 是介词，所以其后通常接名词作宾语。如：
In his opinion, that House had become the great obstacle to progress. 在他看来，这个议院已成为妨碍进步的巨大障碍。
The huge distances involved have proved an obstacle to communication between villages. 遥远的距离成为乡村之间通讯的一个障碍。
The difference in regional house prices acts as an obstacle to mobility of labour. 不同地区房价的差异阻碍了劳动力的流动。
Not being able to pass his mathematics exam proved an obstacle to his career. 他数学考试不及格是他前途上的一大障碍。
▲如果其后接动词作宾语，则要用动名词形式，obstacle to doing sth 的意思是“做某事的障碍”，其中的 to doing sth 用作后置定语修饰名词obstacle。如：
The major obstacle to achieving that goal is money. 达到那个目标的主要障碍就是钱。
Overcrowding remains a large obstacle to improving conditions. 过分拥挤仍然是改善环境的一大障碍。
Mispronunciation can be a serious obstacle to making yourself understood in a foreign language.  说外语时的发音错误会严重妨碍别人对自己的理解。
▲顺便说一句，下面的句子中，obstacle 后接了不定式，但是注意这个不定式不是修饰obstacle的定语，而是目的状语（如果将这些不定式移到句首，句子意思不变）：
Women still have to overcome many obstacles to gain equality.
John was able to surmount all these obstacles to become an outstanding leader.

z老师：

这涉及 an obstacle to sth / doing sth / sb，其中的 to 为介词。

e.g.   A lack of good education is an obstacle to  finding a fine job.