appendix / ә’pendiks/
a small bag of tissue that is attached to the large intestine.
In humans, the appendix has no clear function
a section giving extra information at the end of a book or document
n.附录，附属物；阑尾
pend-词根：挂、靠
depend-依靠

例句

Fortunately she was sent to the hospital for emergency treatment the moment her appendix burst.
幸运的是她的阑尾刚破就被送往医院急救

耶鲁公开课 - 基础物理课程节选
So I don't know your mathematical background, but the textbook has an appendix, which is a reasonable measure of how much math you should know.
我不太清楚你们的数学功底,但教材上有附录,它能清楚地告诉你,你应该掌握多少数学

apprehend[,æpri'hend] hend=hand
to catch somebody and arrest them
to understand or recognize something
to become aware of : perceive
to anticipate especially with anxiety, dread, or fear
vt. 理解；逮捕；忧虑
vi. 理解；担心

例句

The police apprehended the criminal.
警察逮捕了罪犯。
She apprehended the complicated law very quickly.
她很快理解了复杂的法律。
Do you apprehend there will be any difficulty?
你怕有任何困难吗?
to apprehend danger in every sound
风声鹤唳，草木皆兵

understand, comprehend, appreciate, apprehend, grasp
这些动词均有“理解”之意。
understand: 一般用词，很常用，指对事实或意义知道得很清楚。
comprehend: 较正式用词，指对较复杂的事物能透彻理解其意义。
appreciate: 欣赏，指对某事物或意义有正确的认识，对其价值的肯定。
apprehend: 指知道某事物或某观念的大概意义，但未能理解其内涵意义，暗含一知半解意味。
grasp: 从本义抓紧、抓住，引申作“理解、掌握”。

趣味单词

index['indeks] index finger 食指
an alphabetical list, such as one printed at the back of a book showing which page a subject, name, etc. is found on
a collection of information stored on a computer or on a set of cards, in alphabetical order
n. 指标；指数；索引；指针
vi. 做索引
vt. 指出；编入索引中