变成/成为+noun

变成 to become (not used with 着/过, e.g. it is incorrect to say 她变成着/过我的女朋友了；must be used with an object; i.e. a transitive verb)
After a few years, he has become an adult.
几年之后，他已经变成一个大人了。
Jǐ nián zhīhòu, tā yǐjīng biàn chéng yīgè dàrénle.
It used to be a small town, but now it’s a big city.
这里原来是一个小镇，现在变成大城市了。
Zhèlǐ yuánlái shì yīgè xiǎo zhèn, xiànzài biàn chéng dà chéngshìle.
I don’t want to become like him.
我不想变成像他那样的人。
Wǒ bùxiǎng biàn chéng xiàng tā nàyàng de rén.

成为 cannot be used as a predicate alone, it must have an object.
He became a famous actor.
他成为名演员了。
Tā chéngwéi míng yǎnyuánle.
We have become good friends.
我们已经成为好朋友了。
Wǒmen yǐjīng chéngwéi hǎo péngyǒule.
This has become a fact and cannot be changed.
这已经成为事实，无法更改了。
Zhè yǐjīng chéngwéi shìshí, wúfǎ gēnggǎile.

Verb+成为

We want to train him to be a good chess player.
我们要把他培养成为一名好棋手。
Wǒmen yào bǎ tā péiyǎng chéngwéi yī míng hǎo qí shǒu.
It has developed into a new type of city.
那里已经发展成为一个新型城市了。
Nàlǐ yǐjīng fāzhǎn chéngwéi yīgè xīnxíng chéngshìle.

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