正确写法是fallen off，具体释义如下：
读音：[ˈfɔːlən ɒf]
表达意思：脱落；落下。
固定搭配：fallen off a cliff 急转直下；A cap has fallen off 齿冠脱落了；fallen off the tree 从树上掉下来了 ; 掉下树。
例句
1、Attendance at my lectures has fallen off considerably.
听我讲课的学生大大减少了。
2、He felt as if the most crushing load had fallen off him.
他觉得沉重的负担从身上落了下来。
3、The food supply has fallen off.
食物供应已经减少了。
