1. Never trouble trouble till trouble troubles you.
the first and the forth "trouble" are verbs，while the second and the third "trouble" are nouns.
2. I think that that that that that student wrote on the blackboard was wrong.
Can you understand this sentence?
3. I know. You know. I know that you know. I know that you know that I know.
4. We must hang together, or we'll be hanged separately.
"hang together" means unite together，the latter "hanged" means an approach of death penalty.
5. The quick brown fox jumps over a lazy dog.
this sentence includes all the 26 letters of English
6. Was it a bar or a bat I saw?
this sentence, you read from left to right or from right to left, you will get the same result
what is it mean?
What should i do now ? thanks in advance 
