今天学习了九句话，前三句是昨天cash a check部分的内容，后六句讲述另一个大家聚集的原因: now is the time to make justice a reality.
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.
And so. We've come to cash this check, a check that will give us upon demands the riches of freedom and the security of justice.
1. bankrupt的用法
go bankrupt
be declared bankrupt by the court
a bankrupt company
比喻义：morally bankrupt
例句：The opposition attacked the government as morally bankrupt.
2. vault 金库
这一段都在用银行bank和支票check做比喻义，来描述需要兑现的承诺，后面也给出了一系列的意象，比如bank of justice，vault of opportunity，riches of freedom，security of justice，在美国这片充满机遇的土地上，不能用机会渺茫来搪塞对黑人兄弟的承诺，应该给予平等，自由和公正。
3. upon/on demand: when someone asks (formal)
We've come 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 drug of gradualism.
1. this is no time, no time 在这里用作强调，这件事情已经刻不容缓。
2. cool off = calm down
