英语同义句转换1.considering the difficulty,they gave up their plan.

英语同义句转换
1.considering the difficulty,they gave up their plan.
when_____________________,thry.
2.there were 220 children studying in the art school.
there were 220 children___ ____ ____ in the art school.
补充
we are now employing our natural resources ___ ____ they were never used up.