1. 百分之：overbooking 超额订房 | ...per cent 百分之... | reasonable (形)合理的

2. 百分率：pentagon 五边形 | per cent 百分率 | percentage 百分法;百分数

3. 百分数：penstock 压力管 | per cent 百分数 | percentaeg 百分率

4. 百分之几：80.per 按照,经,由 | 81.per cent 百分之几 | 82.percentage 百分数,百分率

1. 百分之…
You use per cent to talk about amounts. For example, if an amount is 10 per cent (10%) of a larger amount, it is equal to 10 hundredths of the larger amount.

e.g. 20 to 40 per cent of the voters are undecided...
20%到40%的选民还犹豫不决。
e.g. We aim to increase sales by 10 per cent...
我们的目标是将销售额提高10%。