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: myanmar government has stated myanmar will become opium-free by 2014. Sentence 2: myanmar government stated myanmar is on track to be drug-free by 2014.
5

Sentence 1: What isn't how what was sold? Sentence 2: It's not how it was sold, gb.
2

Sentence 1: @Frank Apisa, What you want to call it is up to you. Sentence 2: @Cyracuz, What you want to call it is up to you.

2