lean
v. 倾斜；倚；靠

logic
n. reason 逻辑

panic
n. fear; scare

pendulum
n. 钟摆

principle
n. 原则

proportion
n. 比例

recall
v. to remember sth. 回想起

referee
n. sb. In charge of a game in sports ; Here: a person who is asked to settle a disagreement

resist
v. struggle against 抵抗

select
v. to choose

solve
v. to find a way of dealing with a problem 解决

sophisticated
adj. complex 复杂的

Sputnik
n. 前苏联人造地球卫星

stopwatch
n. a watch to time speed 记秒表

string
n. a piece of thread

structure
n. the way in which parts are formed into a whole 结构

superintendent
n. Here: a person in charge of an apartment building 楼房管理处负责人员

swing
v. to move from a fixed point 摆动

system
n. 系统；制度

temptation
n. 诱惑

unit
n. （计量的）单位

warn
v. to advise sb. to do sth. in order to avoid possible punishment or trouble 警告