1、做定語(yǔ)：a difficult task一次很難的任務(wù)。

2、作表語(yǔ)：this task is difficult.這次任務(wù)很難。普通形容詞都可以如上用。

3、句型：it is difficult for *** to do sth:做某事對(duì)某人來(lái)說(shuō)很難.如：it is difficult for me to do the task。

4、名詞是difficulty句型：have difficulty (in) doing sth。