先是

先是

"At first; initially."

In this sentence, '先是' is used to indicate the first action or element in a series of events.

先是他提到这个问题，然后我们展开了讨论。

First, he mentioned this issue, and then we started discussing it.

Here, '先是' shows the primary preference or initial choice when describing habits.

她的早餐先是面包，无聊的时候会选择煎蛋。

Her breakfast is first bread, and sometimes she chooses fried eggs when she feels bored.

In this context, '先是' highlights the order of events occurring in a formal situation.

会议上先是介绍了最新的技术，然后我们进行了产品演示。

During the meeting, the latest technology was introduced first, followed by our product demonstration.