What wasn’t one of the super important trading cities for the Arab empire

Which empire was called "the sick man of europe? "

How did americans disagree over the role of federal and state goverment before and durning the civil war

"if i have seen farther than others," said newton, "it is because i have stood on the shoulders of giants." who were the giants to whom newton was referring? could this be said of any scientific accomplishment? explain.