今天我们要介绍的一个习惯用语是：to let one's hair down。 To let one's hair down 描绘出一幅可爱的画面。过去，西方女子很多都留长头发，出去应酬时把头发盘在头上梳出各种式样来。晚上回家后，她们就把发卡一个个地从头发里拿出来，让头发很自然地披在肩上。 To let one's hair down 的实质意思也就是解除表面的装饰，使一切显得很自然、真实和放松。 To let one's hair down 不一定用于女子，也可以用在男性。下面的例子就可以说明问题：

"The president has to make so many official appearances that he seldom gets a chance to let his hair down and enjoy life like ordinary people."

这句话是说：“总统要出席许多公开场合，因此他很少有机会像普通老百姓那样轻松地享受生活。”

To let one's hair down 也可以用在朋友之间，就像下面这个例子一样：

"Sally, we've been good friends for a long time. But lately I get the idea you are very much upset with me. I wish you'd let your hair down and tell me what's wrong to make you feel this way."

这个人对他的朋友说：“萨莉，我们多年来一直是好朋友，可是最近我感到你对我非常不高兴。我希望你能够坦率地告诉我，到底是些什么事让你这么不高兴。”

matrix
n. 母体, 子宫, 基质, 脉石, 模型, 矩阵
Rome was the matrix of Western civilization.
罗马是西方文明之母。