proportion: （两件事物之间的）比，比例, 通常用于各种成分或分配额的比例等；
rate: 常用于表示速率，利率，出生率，死亡率，兑换率等；
ratio: （表示两个数量之间关系的）比，比例, in direct/inverse ratio to 成正比/反比
percentage: 百分比，百分率；
这是一组在考研和CET-6中经常出现的形近易混词。
transfer: n.转移，转让；(工作的)调动；(旅途中的)换乘，改变路线。
➤ The club's goalkeeper isn't happy here, and has asked a transfer.
这个足球俱乐部的守门员在此过得不愉快，已经要求转会到其他俱乐部。
transaction: n.交易行为，处理。
➤ Transactions of shares on the stock exchange were up today.
今天证券交易所的股票成交额上升了。
transition: n. (从一种情况到另一种的)过渡，更替。
➤ The transition from high school to college can be difficult for students.
对于学生来说，从中学到大学的过渡会是困难的。
transmission: n.传播(比如疾病)；广播。
➤ The transmission of germs can occur by contact, breathing, and eating.
细菌通过接触、呼吸和饮食传播。
transformation: n. (外观或性质的)改变，改观，转变。
➤ His character seems to have undergone a complete transformation since his marrige.
他结婚之后性格判若两人。