阅读下面短文,从短文后所给各题的四个选项(A、B、 C、 D)中选出能填入文中相应数字空白处的最佳选项,并在答题卡上将该项涂黑。

If you asked people what the most important invention has been,many would say the printing press.Others   11   say the wheel.But even though it's   12   whether the appearance of the printing press affected the course of history more than the wheel,the printing press   13   within the top two or three inventions in history.   14   the telephone,the television,the radio,and the computer,the written word was the only way to   15    ideas to people too far away to talk with.Until the 6th or 7th century,all books had to be written   16   .Creating a book was difficult,and very few existed.Therefore,very few people read books. In the 6th and 7th centuries,the Chinese invented a way to print pages by   17   characters and pictures on wooden,ivory,or clay blocks.They would print a page from the block by putting   18   on the block and pressing paper onto the ink.This   19   is called letterpress printing.The invention of letterpress printing was a great advance in communication   20   each block could be inked many times and many copies of each page could be made.Many books could now be made. Therefore,many people could read the same book.