英语 改错1.It is a difficulty for us to distinguish between artificial and natural lakes.2.Thought complicated as the problem is,it can be solved in a few minutes with an electronic computer.

1.a difficulty 改为 difficult,这是it is + adj.+ for sb.to do sth.的句型.
2.去掉thought (可能题目是though),as可以引导倒装的让步状语从句,倒装指的是把句子的表语、状语或动词原形提到句首,但是句子的主谓并不倒装.
此时应注意：一是若提前的表语是没有形容词修饰的单数可数名词,要省略不定冠词,如：
Boy as he was,he behaved like a girl.他虽是个男孩,但举止却像个女孩.
二是若提前的是动词原形(多为不及物动词),与之连用的通常是may,might,will,
would等,且这些词都要保留在原来的位置上(主语后),如：
Try as he would,he couldn’t open the door.他试过多次了,却仍打不开那门.
Search as they would,they would find nobody in the house.无论怎样搜查,他们在房子里仍然没有找到一个人.
其他例子：Tired as I was,I tried to help them.虽然我很累,我还是努力帮助他们.
Hard as they tried,they couldn’t make her change her mind.尽管他们做了很大努力,却没法让她改变主意.