xdf教程练习四－8

Although all the proceedings of the cominess party conference held in Moscow were not carried live, Soviet audiences have seen a great deal of coverage.

答案说选：not all the proceedings of the Communist party conference held in Moscow were carried live

难道这不是改变了句意么？

This is what we called "partial negation"...

Remember what we were told in junior high school? My English teacher told us that "all..not..." does not signify a complete negation but a partial one, it means "不是所有的..." She might be right because some grammar books also hold this view... However, ETS prefers "not all.." to express partial negation, so choose the choice with "not all" if the rest part of the sentence is the same....