The single quotes are used because the double quotes are needed within the drawing command if more than one word is to be drawn, and you cannot have double quotes within double quotes.

使用单引号是因为如果需要绘制多个字，则绘图命令中需要使用双引号，而您不能在双引号中再用双引号。

youdao

Has your eye been drawn to the sole female in the double bass section?

你的眼有否注意到低音提琴部，那个唯一的女性？

youdao

Then the experimental data of joints of top and seat angle with double web angle are analyzed and load-strain curves of member subassemblages key points are drawn.

为此对双腹板、顶底角钢半刚性节点的试验数据进行分析，绘出试件各组合件关键点的荷载-应变关系曲线。

youdao

The side will again be led by Graeme Smith, who hit two double centuries in the drawn series in England in 2003.

BBC: SA recall Nel for England series

It has drawn attention to the double standards that allow Turkey, America's ally, freedom to hammer the Kurds in Iraqi territory.

ECONOMIST: Iran and Iraq

The matinees seemed to go on forever at a time when life held out the same prospect: trailers, cartoons, dumb shorts and then double features, with no distinctions drawn, at least by me, between good and bad, only between boring and not boring.

WSJ: The Hobbit | A Middling Middle-earth