practice
1.practice在英国只用作名词，practise用作动词。但在美国名词和动词都用practice，很少用practise。参见practise
2.下面三句里的a可有可无：
- It is (a) good practice to get up early.
- It is (a) bad practice to go to bed late.
- They went to bed at eight, as had long been (a) common practice.
3.practice in composition里没有the，用in，the practice of composition里有the，用of。
