Example
wǒ我dǎ diàn huà打电话gěi给nǐ你，yì lái一来shì是xiǎng想qǐng请nǐ你chī fàn吃饭，èr lái二来shì是xiǎng想gào su告诉nǐ你wǒ我ér zi儿子yào要jié hūn结婚le了。
我打电话给你，一来是想请你吃饭，二来是想告诉你我儿子要结婚了。
I called you, on the one hand to invite you out to eat, and on the other to tell you my son is going to get married.