How did he become an actor?这句中become为什么不是became?

问题描述:

How did he become an actor?这句中become为什么不是became?

因为是问句, 已经用了did了.

因为前面的 助动词 did 已经表明了时态,所以后面的实意动词 become 要用原形.
翻译:他是怎样变成一个演员的?