一開始

In a sentence

• 一開始，我以為這只是一場普通的聚會。

  At first, I thought it was just a regular gathering.

  In this sentence, '一開始' is used to denote the initial impression or assumption about an event before further realization.

• 一開始，他不太願意參加這個活動，但後來他非常享受。

  Initially, he was reluctant to participate in the event, but later he thoroughly enjoyed it.

  Here, '一開始' functions to illustrate the subject's initial disposition or feelings regarding a matter.

• 我們一開始先討論這個問題，然後再提出解決方案。

  First, we discussed this issue, followed by proposing solutions.

  In this case, '一開始' is used to describe the sequence of actions, marking the initial step in the process.