card指“卡片”；sleeve指“衣袖”。have a card up one’s sleeve直译为“有一张卡片藏在某人的袖子里面”，指某人做某事“心中有数，胸有成竹”。

【例句】
Mr Smith always has a card up his sleeve.
史密斯先生总是胸有成竹。

I believe so. He seems to have a card up his sleeve.
我相信他能。他看起来胸有成竹。