四． 悬垂修饰语（dangling modifiers）
　　所谓悬垂修饰语是指句首的短语与后面句子的逻辑关系混乱不清．例如：at the age of ten, my grandfather died. 这句中＂at the age of ten＂只点出十岁时，但没有说明” 谁”十岁时．按一般推理不可能是my grandfather, 如果我们把这个悬垂修饰语改明确一点，全句就不那么费解了．
　　改为：
　　when i was ten, my grandfather died.
　　例１． to do well in college, good grades are essential.
　　剖析：句中不定式短语 “to do well in college” 的逻辑主语不清楚．
　　改为：
　　to do well in college, a student needs good grades.