Evaluate the similarity between them and classify them into classes from 0-5 as follows:
0 : The two sentences are completely dissimilar.
1 : The two sentences are not equivalent, but are on the same topic.
2 : The two sentences are not equivalent, but share some details.
3 : The two sentences are roughly equivalent, but some important information differs/missing.
4 : The two sentences are mostly equivalent, but some unimportant details differ.
5 : The two sentences are completely equivalent, as they mean the same thing.

Sentence 1: A dog biting on a can. Sentence 2: A dog opens a can of food.
2

Sentence 1: Obama widens lead over Romney despite jobs data: Reuters/Ipsos poll Sentence 2: Romney takes lead over Obama with convention "bounce": Reuters/Ipsos poll
1

Sentence 1: japanese prime minister junichiro koizumi said the shift of the rods was proactive. Sentence 2: in 2002 japanese prime minister junichiro koizumi attended an summit in north korea with north korean leader kim jong il.

1