I think you want to ask the Mandarin phrase “因为 (yīnwèi).” It means “because.” This Mandarin phrase is often used to lead an adverbial clause of cause. 
Zhè bìng bú shì yīnwèi tāmen yǒu qián, ěr shì yīnwèi…
这并不是因为他们有钱，而是因为…
It is not because they are rich, but because…

Learn more:
In order to tell the results of an adverbial clause led by the Mandarin phrase “因为(yīnwèi),” we often use “所以(suǒyǐ) so.” 
For example:
Yīnwèi xiàyu, suǒyǐ bù néng qù pá shān le
因为下雨，所以不能去爬山了。
We can go hiking because it is raining.