compel : 指在法律、权力、力量或行动等的驱使下被迫而为。
- The law can compel fathers to make regular payments for their children.
- I feel compelled to write and tell you how much I enjoyed your book.
force : 指用个人意志、权力、权威或暴力等，迫使他人改变看法或做本不愿做的事。
- The President was forced to resign.
- I was forced to take a taxi because the last bus had left.
constrain : 侧重施加约束力或有约束作用的影响，也指环境对人强加的影响迫使人去做某事，尤指受良心、情感等内在力量驱使去做某事。
- The evidence was so compelling that he felt constrained to accept it.
oblige : 指由于生理上或道德上的需要，促使某人做某事，也指有权威的人或机构迫使某人做某事，还可指在特定情况下被迫作出的反应。
- Parents are obliged by law to send their children to school.
- The storm got worse and worse. Finally, I was obliged to abandon the car and continue on foot.