we have been informed that he had done

we have been informed that he had done

选B.主体句式中that引导了第一个宾语从句he had done __ visits were essential by eleven o'clock last night ,选B就会使这第一个宾语从句里又套了第二个宾语从句__visits were essential ,而what在这第二个宾语从句里做主语,成立.选A是使第一个宾语从句中包含一个定语从句,修饰all visits,但这样定语从句中就会缺少主语（were前面）,而在定语从句中主语是不能省略的,不成立.选C两个错误,1.that做指示代词时只能修饰单数名词 2.定语从句中仍然缺少主语选D句式混乱,改为.he hade done all visits that were essential.则正确,这时all visits做宾语,that were essential成为定语从句修饰宾语,即做宾补.======以下答案可供参考======供参考答案1:选B，what。句意判断：我们已经被告知到昨天晚上7点之前，他已经做过了必要的访问/视察。选项辨析： ①如果用A、C、D中的某个，原句需变为：We have been informed that he had done 【all the】_ visits【that】 were essential by eleven o'clock last night 。因为，直接用all,少了定冠词；而且，句子结构混乱而导致错误：that宾语从句中，出现了两个非并列的谓语动词【had done 】和【were essential 】。 用that作指示代词时，需修饰单数名词，直接错误； 用all that,all 是不定代词，应该是先行词，与visits重复，错误。 ② 用what，what visits were essential =【all the】 visits【that】 were essential 。供参考答案2:选b排除法选其他的话，从句中有两个谓语动词，不合理供参考答案3:B。宾语从句。这里what=the things that供参考答案4:we have been informed that he had done __ visits were essential by eleven o'clock last night.A all B what C that D all that答：我怀疑题目有误，这个visits有点莫名其妙！搜索网络，找不到此题。去掉它，句子才有意义：We have been informed that he had done ______ were essential by eleven o'clock last night.A all B what C that D all that答：B译：有人告诉我们说他在昨天晚上11点之前就已经做好了那些重要的事情。析：从句意上BD都可以。但是what=the things that..., 从句谓语可以用were,但all表“事情”时，为单数，如将were改为was,则BD都可以。供参考答案5:b

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