cave
A hollow or natural passage under or into the earth, especially one with an opening to the surface.
A storage cellar, especially for wine.
To dig or hollow out.
To cause to collapse or fall in. Often used with in: The impact caved in the roof of the car
vt. 使凹陷，使塌落；在…挖洞穴
vi. 凹陷，塌落；投降
n. 洞穴，窑洞

例句：
The top of the car was caved in by the impact.
那个冲击使得车顶塌了。
Our cellar caved during the earthquake.
地震时,我们的地窖塌陷了。
The school committee finally caved in to the demands of parents and teachers.
在家长和老师的要求下,学校委员会最后终于屈服了。

cavern
A large cave.
A large underground chamber, as in a cave.
tr.v. cav·erned, cav·ern·ing, cav·erns
To enclose in or as if in a cavern.
To hollow out.
n. 洞穴；凹处
vt. 挖空；置…于洞穴中

cavernous
Filled with caverns.
Resembling a cavern, as in depth, vastness, or effect: a cavernous yawn; cavernous echoes.
adj. 似巨穴的；洞穴状的；凹状的；瓮声的

cavity
A hollow; a hole.
A hollow area within the body: a sinus cavity.
A pitted area in a tooth caused by caries.
n. 腔；洞，凹处；【医学】牙腔，蛀牙的洞

concave
hollowed or rounded inward like the inside of a bowl
arched in : curving in ― used of the side of a curve or surface on which neighboring normals to the curve or surface converge and on which lies the chord joining two neighboring points of the curve or surface
a concave line or surface
adj. 凹的，凹面的
n. 凹面
vt. 使成凹形

例句：
The palm of one's hand is slightly concave.
人的手掌是微凹的。

excavate
To make a hole in; hollow out: excavate an ore-rich hillside.
To form by hollowing out.
To remove by digging or scooping out.
To expose or uncover by or as if by digging
To engage in digging, hollowing out, or removing
vt. 挖掘；开凿
vi. 发掘；细查

例句：
They plan to excavate a large hole before putting in the foundations.
他们计划打地基前先挖个大洞。
The archaeologists excavated a buried city.
考古学家发掘出一个埋在地下的城市。

excavator
a large machine that is used for digging and moving earth
a person who digs in the ground to look for old buildings and objects
n. 挖掘机；开凿者；打洞机

词源小故事

Quiz 测验

　　quiz可以指课堂上的“测验”、“小考”等，比test（测验）还要小些；也可指广播、电视节目等中的“智力测验”、“一般知识测验”等。如Follow Me（《跟我学》，BBC的电视教学节目）中的“London Quiz”（伦敦知识测验）

　　据说“quiz”一词是18世纪末爱尔兰共和国首都都根据柏林一家剧院的经理James Daly创造的。一天，他和别人打赌说他可以在一夜之间造出一个新的、毫无意义的、却又不能为人们接受的词来。他花钱雇了一些顽童，连夜在都柏林城中的每一面墙壁上用粉笔写上“quiz”的字样。第二天一早，人们发现了这个词，但谁也不知道它的含义是什么，于是这个毫无词义的“quiz”不久就有了“智力测验”、“恶作剧”等词义。