The concept of reducibility is central to understanding the relationships between different computational problems.
The magi, as you know, were wise men—wonderfully wise men—who brought gifts to the Babe in the manger. They invented the art of giving Christmas presents. Being wise, their gifts were no doubt wise ones, possibly bearing the privilege of exchange in case of duplication.
我想卖出一百万张唱片,我卖出了一百万张。我想获得白金唱片;我获得了白金唱片。我从15岁开始就一直在不停地工作。我甚至不知道如何放松。