【问】 It has been that almost sixty of at the Badlands National Monument is vegetation. (TOEFL， 1987)

我看不出这个句子有什么错误。

【答】 应注意per cent(或写作percent)用作名词时，无复数形式：

1. 45 per cent of Americans were against it. (EED)

百分之四十五的美国人反对它。

2. Ten per cent of the pupils are absent today. (JED)

今天有百分之十的学生缺席。

3. Prices have risen 6 percent in the past year. (MED)

在过去年里价格上涨了百分之六。