It was after the invention of printing ________ to publish large numbers of books and pictures．A.were people ableB.that people were ableC.when were people ableD.people were able
网友回答
B解析强调句型；强调部分是after the invention of printing后面接连词that以及句子的其他部分。正是在印刷术发明之后人类才能大量地出版图书。