我们认为汤姆一定和朋友野营去了的英文 We thought that Tom ____ ____ ____ with his friends.

这里一定要用完成时态,且是情态动词的完成时,即must have done.但你的空格只有三空,我只能must have camped.若有四空must have gone camping若有五空must have gone for camping.
另外,英语情态动词中一个高频考点即情态动词加have done的结构.这类结构一般表示推测,还可表示虚拟,都是很重要的.