① fail通常有下面几种用法。
（1）表示“失败”，fail是不及物动词，后不可跟宾语。
His plan failed. 他的计划失败了。
She did her best but she failed at last. 她尽了最大努力，但是最后还是失败了。
（2）表示“不及格，没通过（考试）”，fail常用作及物动词，后跟exam，maths，English等学科名词。
She failed the exam. 那次考试她不及格。
He failed the maths exam again. 他数学考试又没有及格。
She failed Chinese. 她语文考试不及格。
“某学科考试不及格”也可用“fail in+学科名词”表示。
She failed chemistry. 她化学考试不及格。
（3）fail to do sth. 表示“没有做某事，没有能够做某事。
He failed to swim across the river. 他没能游过这条河。
She failed arriving on time.
She failed to arrive on time.
她没有准时到达。
② not/never fail to do相当于cannot but do，be sure to do，意为“务必，必须，一定”，要注意译法。
If you pass the entrance examination，don't fail to phone me. 如果你通过了入学考试，务必给我打电话。
She never fails to attain her goal. 她一定会达到目的。
③ lose为及物动词，后接match，game，battle，war，case等。另外，表示“被……打败”或“输给……”时，常用be beaten by sb. 或be defeated by sb.。
Class A was defeated by Class B in the game. A班在比赛中输给了B班。