The main point of this excerpt is that African-Americans were not considered US citizens.
In the Supreme Court case Dred Scott vs. Sandford, Scott is suing for his freedom from slavery. This is because his master brought him to the Wisconsin territory, a territory where slavery was outlawed.
However, the Supreme Court ruled against him. The reason why they ruled against him is based on the excerpt above. The Declaration of Independence did not make it blatantly clear that slaves were considered citizens. Since they were not considered citizens, they had no legal rights that slave owners had to respect.
In 1934 the Communists suffered huge losses against the nationalists in the Chinese Civil War. Faced with the prospect of annhilation the leaders of the Comunist army shose to start what is now called the Long March. This was a tactic of withdrawal into mountainous areas, some 2500 miles to the north and west. The purpose was simple: survival. By undertaking a tactical withdrawal the Communists could ensure that they still had an effective fighting force; could select easy to defend locations; could regroup and could ensure that the Nationalists supply lines were long and susceptible to attacks.
He was most famous for inventing a new style of "singing" called scat singing.
I don’t know if this is right but I am guessing Britain and France
Answer: When they sign a yellow- dog contract they are agreeing to the company which forces each individual worker to sign, on the penalty of not getting the job (or if he already has the job, of losing it), binding the worker to surrender his right to organize. In other words, yellow dog binds the worker not to join a union.