UNIT5
1.Stretched metal spring
2.coal-fired power plant
3.Polar Regions
4.Climate change
5.Rise in sea level
6.Acid rain
7.global warming
8.environmental problems
9.polluting gases
UNIT6
1.fixed volume
2.close together
3.further apart
4.zipper storage bag
5.floats
6.sinks
7.particle
8.substance
9.matter
10.density
11.pressure
12.particle theory
OTHERS
1.probable
2.determine
3.aerosol can
4.zipper storage bag
5.airship
6.replace
7.purpose
8.sealed
9.hydrogen