这样说有什么语法根据？

50.   That educators have not anticipated the impact of microcomputer technology can hardly be said that it is their fault: Alvin Toffler, one of the most prominent students of the future, did not even mention microcomputers in Future Shock, published in 1970.

(A) That educators have not anticipated the impact of microcomputer technology can hardly be said that it is their fault

(B) That educators have not anticipated the impact of microcomputer technology can hardly be said to be at fault

(C) It can hardly be said that it is the fault of educators who have not anticipated the impact of microcomputer technology

(D) It can hardly be said that educators are at fault for not anticipating the impact of microcomputer technology

(E) The fact that educators are at fault for not anticipating the impact of microcomputer technology can hardly be said

Grammatical construction

Although it is possible o begin a sentence with a subordinate clause beginning with that, this inverted construction often results in errors such as those found here. In the original sentence, the subordinate clause that ... technology is followed by the main verb, can ... be said, but then the verb is followed by yet another subordinate clause, that it is their fault.
                    The best way to solve this problem is by putting the sentence in the expected order, with the main clause (It can hardly be said) preceding the subordinate clause (that ...). For greater clarity and concision, the two subordinate clauses should be condensed into one: educators are at faultfor anticipating the impact of microcomputer technology.

A     Inverting the usual order results in an ungrammatical construction in which the main verb is both preceded and followed by a subordinate clause

B     Can hardly be said to be at fault does not grammatically complete the subordinate clause

C     Construction that it is ... who have not is wordy and awkward; it also distorts meaning and lacks completion

D     Correct. This sentence has the main clause followed by one subordinate clause correctly introduced by that.

E      The fact is wordy; the inverted construction does not successfully convey the meaning of the sentence

The correct answer is D.

这题高亮部分的解释读了很多边都不能理解，到底是想说什么呢？从句不能同时做主语和宾语么？是这个意思么？那么这样说的句法根据又是什么呢？

umm...那句话的意思是，谓语动词的两边不能都是从句，否则ungrammatical.