characteristic
a. showing the individual character 表示特性的

essential
a. necessary; most important

organization
n. the act of organizing; an organized body or system

repetitive
n. the act of organizing; an organized body or system

repetitive
a. of or characterized by the act of repeating

repetition n.

function
n. special duty (of a person) or purpose (of a thing) 职责，功能，作用

outdated
a. no longer in general use; old-fashioned 过时的

quicken
v. make or become quick(er)

acceleration
n. 加速

dramatize
vt. put into dramatic from; express or represent (sth.) in a dramatic or exaggerated way

account
n. report or description

transportation
n. the business of carrying people or goods from one place to another 运输

transport vt.

BC abbr.
Before ( the birth of) Christ 公元前

available
a. capable of being got, obtained, used, etc. 可获得的；可利用的

camel
n. 骆驼

caravan
n. (往返于沙漠地带的）商队

average
vt. have as an average 平均为

per
prep. for each 每

mph
abbr. miles per hour

chariot
n. two-wheeled carriage pulled by horses （古时）双轮马拉战车

maximum
n. & a. (being) the largest number, amount, etc.

roughly
ad. about; more or less but not exactly

impressive
a. making a deep impression on the mind and feelings 给人深刻的印象的

exceed
vt. go or be beyond a limit, measure, or degree 超过

coach
n. large, old-fashioned, closed carriage pulled by horses 四轮大马车

operate
v. (cause to ) work, be in action

mere
a. nothing more than

locomotive
a. railway engine 火车头

race
n. main division of any living things; nation or tribe 属；人种

airplane
n. 飞机

flick
n. sudden, light blow or stroke; sudden short movement 轻弹；突然的轻快动作

rocket
n. 火箭

capsule
n. the part of a spaceship in which the pilots live and work and from which the engine is separate when the takeoff is completed 宇宙密封舱