He said --- the book was very interesting and --- all the ch

that；that 才是对的.
that the book was very interesting and that all the children liked to read it 是并列做said 的宾语从句.如果第二个空填which则句子就不通了.此外,这两个that可以省去,因为宾语从句的that可以省略.当然,也可以保留第一个that,而第二个that承上省略.