I found it difficult to work out the problem.中it可以换成it's吗?为什

I found it difficult to work out the problem.中it可以换成it's吗?为什 He found it difficult to work out the problem. I found it difficult to work out the problem without your he I found it easy (to work) out the problem in this way. 括号内为什 The maths problem is very difficult,.I work it out,though 为什 i can't work out the problem.it's too difficult同义句转换 i have So difficult it to work out the problem that i dicided to as So difficult __ it to work out the problem that I decided to It’s difficult for me to work out the math problem(同义句改写） It's clever for him to work out the difficult math problem.单 I think .difficult to work out the problem.A,it B.this C.tha I thought it difficult for me to work out the problem 如果对 是不