If you feel __,take the medicine at once.

问题描述:

If you feel __,take the medicine at once.
A pain B painful C well D badly请告诉我答案及缘由,顺便问一下:pained painful的区别

B.feel是系动词,后跟形容词,故根据题意,选painful.pained:显出痛苦的,主语一般是人;painful:令人疼痛的,主语一般是物.