this is so difficult a question that none of us can answer itit要不要加在answer后面?我认为a question是先行词,that引导定从

this is so difficult a question that none of us can answer itit要不要加在answer后面?我认为a question是先行词,that引导定从
this is so difficult a question that none of us can answer it
it要不要加在answer后面?我认为a question是先行词,that引导定从

this is so difficult a question that none of us can answer itit要不要加在answer后面?我认为a question是先行词,that引导定从
这个是so...that句型,that后面是结果状语从句,后面要加it的.句子意思是：这个问题太难了,我们谁都答不出来.