It is obvious today that America has defaulted on this promissory note insofar as her citizensof color are concerned. Instead of honoring this sacred obligation, America has given the Negro people a bad check; a check which has come back marked "insufficient funds." But we refuse to believe that the bank of justice is bankrupt. We refuse to believe that there are insufficient funds in the great vaults of opportunity of this nation. So we have come to cash this check — a check that will give us upon demand the riches of freedom and the security of justice. We have also come to this hallowed spot to remind America of the fierce urgency of now. This is no time to engage in the luxury of cooling off or to take the tranquilizing drugof gradualism. Now is the time to make real the promises of Democracy. Now is the time to rise from the dark and desolate valley of segregation to the sunlit path of racial justice. Now is the time to open the doors of opportunity to all of God's children. Now is the time to lift our nation from the quicksands of racial injustice to the solid rock of brotherhood.
n. 机会,时机