顺便【shùnbiàn】

顺便 marks an action you do because you're already doing something else – no extra trip, no extra effort. It goes before the verb of that second action.

The main action comes first, and 顺便 heads the second clause. If the second clause has its own subject, 顺便 follows it.

顺便问一下

顺便 + 问 / 说 brings in a side question or remark: "by the way". It is polite, because it marks the question as minor.

Before the verb, not at the end

"While you're at it" closes an English sentence. 顺便 has to sit before the verb it goes with.

• × 你去超市买牛奶顺便 → 你去超市，顺便买点儿牛奶
• × 我顺便，看看朋友 → 我顺便看看朋友