my cousin ( be ) an environmentalist for three years

many nations ( purchase ) wind power from the UK now

nowadays, non-renewable energy sources ( limit )

the world ( use ) mostly renewalbe energy sources in the future

as planned, more dams ( install ) to produce hydropower next year

my cousin ( be ) an environmentalist for three years

many nations ( purchase ) wind power from the UK now

nowadays, non-renewable energy sources ( limit )

cần gấp mn ơi

( 2m+7n-9mn ) - ( 6mn + 15m - 27n - 21) 

Tính 

( a+b ) - ( a-b )

( xy+yz-x ) + ( x+xy-2yz )

( 2m+7n-9mn ) - ( 6mn + 15m - 27n - 21)