for fear of 是用于表示原因、理由的介词词组，通常作“以免；预防”解，如：- I won't go out today for fear of catching cold. - He ran away for fear of being hurt.in case of则是表示条件的介词词组，作“如果”解，如: - In case of rain, the meeting will be put off. in case 可以单独使用，如：Take the umbrella, just in case....
