The verb that is being used in the given sentence above is "has eaten". The principal part of the verb being used is a past participle. The past participle of the verb is used when the action has been completed some time in the past. This action "has eaten" all of the grapes was done and completed in the past.
Just think of two things that could be compared in an unusual way! A metaphor is just a comparison that doesn't use "like" or "as". For example, a simile would be "My love is like a rose" but a metaphor would be "My love is a rose" If you think of it this way, it might be easiest to think of a simile then take away "like" or "as". Be creative with it and have fun
The correct answer is <em>who.
</em>The teacher knew it was Sam who was passing notes.
It would be <em>whom </em>in this case:
The teacher knew it was Sam <em>whom </em>they were passing notes to.