At first I thought he was shy, but then I discovered he was just not interested in other people.

起先我以为他腼腆，后来才发现他对别人没兴趣。

《牛津词典》

At first I thought of buying you a fountain pen, but you've already got one.

开始我想到给你买支钢笔，不过你已经有一支了。

youdao

“At first I thought glove, ” Gelton says.

“起初我还以为是手套，”济丹说。

youdao

At first I thought the city was empty. The buildings all were empty and in poor repair.

VOA: special.2010.07.17

After Gatsby's death,Nick Carraway, the storyteller,says: "I thought of Gatsby's wonder when he first recognized the green light at the end of Daisy's boat dock.

VOA: special.2010.11.28

At first I thought I ought to prepare--to read articles on school vouchers and interview experts.

CNN: Talking Race With The President

"Caller ID was blocked, so at first I thought it was a telemarketer, " his message joked.

WSJ: SpaceX Craft Rehearses Moves

At first I thought it might actually be too hard for my poor Monk.

FORBES: Connect