vapor
加入词篮steam
solid
liquid
fluid
gravity
rate
flexibility
spring
stretch
shrink
magnet
light
ray
X-ray
reflection
laser
focus
quake
interference
echo
wave
frequency
period
microwave
short-wave
radar
potential
voltage
resistance
volt
conductor
semiconductor
pressure
stress
strain
mass
stay
variety
species
energy
power
sheer
environment
conservation
protection
wildlife
pollution
resource
erosion
greenhouse
lead
stack
exhaust
evolution
primitive
civilization
civilization
culture
respect
bow
arrow
stick
origin
source
tradition
convention
usage
antique
dig
ruin
sacrifice
language
idiom
dialect
accent
pronunciation
stress
word
alphabet
initial
spelling
spell
vocabulary
stem
root
meaning
dictionary
recognition
identification
compound
context
outline
philosophy
philosopher
material
ingredient
stuff
thing
stereotype
