It's worth noticing that it's usually the vowels which have variants, though sometimes it may be the consonants.

值得注意的是， 通常是元音有变体，但有时可能是辅音。

The hidden reasons behind the phenomenon are as following: Primarily, it is worth noticing that the benefit derived from reading is obviously remarkable, enabling the reader to enrich his knowledge.

其背后隐藏的原因如下： 首先， 值得注意的是， 阅读的收益明显显着， 使阅读者的知识得以丰富。