B/1-Air pollution/common environmental problem/throughout/world
2-Therefore/if/want/protect/environment/pollution/we/should/do/following/thing
3-Firstly/we/should/reuse/used class/newspaper/bottle/instead/throw/thêm/away
4-Secondly/we/should/travel/bicycle/public transport
5-Thirdly/we/must/stop/burn/coal/produce/electricity
6-If /we/try/do/all/we can,/environment/cleaner.
D/1-Sun/effective/source/power
2-It/be/cheap
3-It/be/clean
4-It/not cause/pollution
5-Solar panels/be installed/roof/house/receive/energy
/the sun
6-It/can/store/a number of days
7-It/be used/cloudy days
8-Solar energy/provide/enough power/world's population
9-We/save/natural resources/use/solar energy/instead/gas,oil and coal
10-Therefore/lot/countries/world/already/use/solar energy