a line of trees作主语谓语用单还是复数

问题描述

a line of trees作主语谓语用单还是复数，比如 a line of trees 后的动词用stand 还是 stands？

老师答疑

陈老师：

当“a line of+复数名词”用作主语时，其谓语动词可用单数（视为整体）也可用复数（侧重个体）。如：
A line of low hills was seen in the distance.（《张道真英语用法》）
A ragged (= not straight) line of people were waiting at the bus stop.（《剑桥高级英语词典》第3版）

黎老师：

a line of ... 作主语谓语用单数。例如：
A line of people or things is a number of them arranged one behind the other or side by side.（《Collins  COBUILD Advanced Learner's English - Chinese Dictionary 》line 词条）