▲你说词典标明 crop 是可数名词。没错，crop 表示作物或庄稼时，它是可数名词，但在用法上要注意：

(1) a crop 指一种作物或庄稼，不指作物或庄稼中的一棵或一株。如：

Oats is a crop grown widely in Europe. 燕麦是一种欧洲广泛种植的作物。

(2) crops 指多种或各种作物或庄稼。

They planted different crops in valleys. 他们在山谷种各种庄稼。

All crops were ruined by the flood. 所有庄稼被洪水毁掉了。

(3) 指同一种作物或庄稼时，即使其数量很多，也不用复数。比较：

all crops 指所有（不同种类的）农作物

all of the crop指某种农作物中的全部

▲现在看看2008年广东卷这篇文章的相关内容：

It is said that a short-tempered man in the Song Dynasty (960—1279) was very anxious to help his rice crop grow up quickly. He was thinking about this day and night. But the crop was growing much slower than he expected.

One day, he came up with an idea that he would pluck up all of his crop a few inches. He did so the next day.

He was very tired after doing this for a whole day, but he felt very happy since the crop did “grow” higher.

His son heard about this and went to see the crop. Unfortunately the leaves of the crop began to wither.

说明：其中的 all of his crop 用的是单数的crop，而没有用复数的 crops，因为作者是指此人所种植的 rice crop (见原文中的 was very anxious to help his rice crop grow up quickly)，是指一种庄稼，所以要用单数。