A line graph shows how the value of something changes over time. The vertical axis shows quantities, e.g. numbers, percentages or money. The horizontal axis shows different points in time, usually months or years. Different quantities measured at different points in time can be joined using a continuous line to show a trend or how these quantities change, e.g. increase, decrease, or stay the same. More lines (different colours or styles) can be used for different categories. The key explains which categories are being measured.

线形图显示了某一事物的价值如何随时间变化。纵轴显示数量，如数字、百分比或金钱。横轴显示不同的时间点，通常是月或年。在不同的时间点上测量的不同数量可以用一条连续的线连接起来，以显示趋势或这些数量如何变化，例如增加、减少或保持不变。不同的类别可以使用更多的线（不同的颜色或样式）。钥匙说明正在测量哪些类别。

The diagram shows the enrolment of Iranian, Greek and Turkish students at Sheffield University from 2005 to 2009. During this period, enrolment of both Iranian and Turkish students rocketed sharply. However, Greek admissions dropped significantly with numbers being almost the reverse of those for Iranian students.

Iranian numbers grew steadily up to 2008 followed by a sharp rise reaching almost 160 students in 2009. Similarly, the numbers of Turkish students showed steady growth throughout the period from about 20 in 2005 to over 120 in 2009. In contrast, enrolments of Greek students decreased dramatically from a high of 180 students in 2005 to just about 70 in 2007. Numbers then levelled off throughout 2007 finally dropping again to a low of around 45 in 2009. A further point of interest is that from 2007 to 2008, enrolments from all three countries were very similar, the average difference being approximately 20 students.

Overall, the graph highlights a considerable difference between growth in Iranian and Turkish enrolments but reduction in Greek enrolments.

该图显示了2005年至2009年谢菲尔德大学伊朗、希腊和土耳其学生的入学情况。在此期间，伊朗学生和土耳其学生的入学率都急剧上升。然而，希腊语录取人数大幅下降，人数几乎与伊朗语学生的录取人数相反。

伊朗学生人数在2008年之前稳步增长，2009年急剧上升，达到近160人。同样，土耳其学生的人数在整个期间也稳步增长，从2005年的20人左右增加到2009年的120多人。相比之下，希腊学生的入学人数则从2005年的180人大幅下降到2007年的70人左右。然后，在整个2007年，人数趋于平稳，最终再次下降到2009年的45人左右。另一个值得关注的问题是，从2007年到2008年，三个国家的入学人数非常相似，平均相差约20人。

总的来说，该图突出显示了伊朗和土耳其入学人数的增长和希腊入学人数的减少之间的巨大差异。