what is ----troubles you most from time to time?A it that B that C which D it 为什么选A 而不选D 返回语序,用 it is what 作主语不对吗?

what is ----troubles you most from time to time?A it that B that C which D it 为什么选A 而不选D 返回语序,用 it is what 作主语不对吗?
what is ----troubles you most from time to time?
A it that B that C which D it 为什么选A 而不选D 返回语序,用 it is what 作主语不对吗?

what is ----troubles you most from time to time?A it that B that C which D it 为什么选A 而不选D 返回语序,用 it is what 作主语不对吗?
这是一句强调句,去掉it is 和that 以后还是成立的