在雅思写作中，描述饼状图上的百分比时，你可以使用以下句型：

1. 使用“the percentage of”或“the proportion of”来表达饼状图中各部分所占的比例。

例如：

The percentage of full-time working mothers with 0 to 2-year-old children to care for is 11%.

The proportion of students interested in science is significantly higher than that of students interested in the arts.

2. 确保百分比数值正确，并以百分数的形式呈现。

例如：

Sixty percent of the students prefer online learning.

Forty percent of the survey respondents believe climate change is the most pressing issue.

3. 在描述时，可以简要概述饼状图所展示的信息，并在细节部分深入描述数据。

例如：

The pie chart illustrates the distribution of students' extracurricular activities across different categories, with each category represented by a slice of the pie. The largest slice, at 40%, represents students involved in sports activities.

The graph displays the proportions of different age groups within a population, with the largest group, at 60%, being those aged between 30 and 49 years old.

记得在写作时保持语言清晰、准确，并且注意句子的连贯性和逻辑性。希望这些信息对你准备雅思写作有所帮助!