改成一般疑问句：Somebody has already taken the rubbish away from the classroom.

Somebody has already taken the rubbish away from the classroom。

改成一般疑问句：Has anybody taken the rubbish away from the classroom yet?

在把肯定句改成一般疑问句的时候，要注意句中是否有already、some、something、somebody等词，如果有某些情况下也必须进行改变：

already要改成yet；

some、something、somebody等分别改成anyanything、anybody等。