difficult
1.difficult是“使人感觉困难的”，不是“感觉困难的”，如可以说This is a difficult task和This task is difficult to do，不可说I am difficult to do the task或I am difficult in doing the task。I am difficult作“我使人难以应付”解，又如：He is a difficult boy.
2.This task is difficult to do里的to do不可改作to be done。同样地，可以说difficult to answer，difficult to understand等，不可说difficult to be answered，difficult to be understood等。
3.difficult后面可以接of和表示动作的名词，如difficult of access，difficult of explanation和difficult of performance。
