Rules for when you use "a" "an" and "the"

When grendel speaks of unferth and says "i could crush him like a fly" what literary device is being used

What does water came out from a rock mean in this poem and why is it compared to the radio waltz? time was away and somewhere else. the waiter did not come, the clock forgot them and the radio waltz came out like water from a rock: time was away and somewhere else.

What is frankensteins main goal after he sees the monster for the first time