用作定语
▲～+n.
 Keep the chemicals at a constant temperature.把这些化学用品保持在恒温中。
Her constant nagging drives me crazy.她不停地唠叨使我发狂。
The seeing eye dog was the blind man's constant companion.导盲犬是盲人的忠实伙伴。
用作表语
▲S+be+～
 In our world nothing seems constant.在我们这个世界上，似乎没有东西是永恒不变的。
In history, change is constant.在历史上变化是不断的。
He alone remained constant.只有他一个人忠贞不渝。
▲S+be+～+prep.-phrase
They were constant in friendship.他们之间的友谊永恒。
He is constant to his friend.他忠于朋友。

constant有时还可用作名词,意为“常数,恒量”。例如:
If the number never varies, we call it constant.如果这个数字从不改变,我们就叫它常数。

［同义词］   fixed, stable, unchanging
［反义词］   irregular, periodic
［词源］＜拉丁语constans(一直站立的)