The line from the poem The Lake of the Dismal Swamp by Thomas Moore that
is the best example of Alliteration is the very first, where Moore uses
three words with the same first letters.
There are multiple suffixes that can be added to depend, it usually varies based on what you mean. Here are some possibilities, I have bolded the suffix in each word to make it easier to understand:
1) dependable
2) dependence
3) dependent
Because and at are the two preposition in it