例句-1:Gramma wanted us all to fly out to see her at Christmas, but we were against the idea. Then she offered to buy our plane tickets, which changed our minds almost immediately. She knew that playing that trump card would make the difference.
例句-2:The case against the accused man looked all but lost. Fortunately for him, his attorney was able to produce a trump card, a surprise witness who supported the defense. Instead of going to jail, the defendant was found innocent.