a. 人种的, 种族的【医】 种族的

◆记忆方法一：
分析：race（种族）的形容词形式。

◆记忆方法二：
联想方式：r[形似]斧子，a一，cial[谐音]手
记忆方法：用斧子放在一只手上是种族的习惯。

face/facial/surface/deface/preface/mask/race/racial/cheek/cheer
记忆：
1. face [ feis ] n. 脸, 面容, 表情 vt. 面对, 面向 vi. 朝, 向 However hard it is, you must face the sad truth.不管有多难，你都得面对这令人哀伤的真相。
2. facial [ 5feiFEl] adj. 面部的 His facial expression suggests that the battle was lost.他的面部表情表明这场战斗输了。
3. surface [ 5sE:fis ] sur-face n. 表面 There are some black dots on the surface of the desk.课桌表面有几个黑点。
4. deface [ di5feis ] de-face vt. 损伤外观, 丑化, 使失面子 The defaced machine will be sent back to the factory.表面有损的机器将被送回工厂。
5. preface [ 5prefis ] pre-face n. 序文, 绪言, 前言 He invited Mr. Zhang Xianliang to write the preface of his new book.他邀请张贤亮先生为他的新书作序。
6. mask [ mB:sk ] m-ask m, 蒙，蒙面 n. 面具, 掩饰 Everyone wore a strange mask at the party.聚会上每个人都戴着奇怪的面具。
7. race [ reis ] n. 种族,赛跑 vi. 赛跑, 疾走 We must race with time.我们必须和时间赛跑。
8. racial [ 5reiFEl ] adj. 人种的, 种族的, 种族间的 Any racial discrimination will be seriously punished here.在这里任何种族歧视行为都将受到严厉的惩罚。
9. cheek [ tFi:k ] n. 颊 The man with high cheeks are checking the machine.面颊很高的那个人正在检查机器。
10. check [ tFek] vt. 检查, 制止, 核对 Any truck going through the customs will be under check.任何过海关的车都将接受检查。
11. cheer [ tFiE] n. 愉快, 欢呼 n. (对)欢呼 Cheer up! 振作起来！提起精神！The good news cheered us up.好消息使大家都振奋起来。
12. cheers [ tFiEz] int. 干杯
另类阅读：
The facial expression on his cheek cheered everyone standing on the surface of the platform. What he would face is not to deface the school but to write a preface for a book about the school.