The physics problem is too diffcult for us_____.
问题描述：
The physics problem is too diffcult for us_____.
A;work it out B;to work it out C;to work out it D;to work out
以及选的理由.
答
有“It is difficult for sb.to do sth.”这个句型吧;
Work out = Vi.+ Adv.
it 是 pron.放中间
所以选择B吧.