The history teacher said to them,“The Chinese Communist Party was founded on July 1st ,1921.
这题变成间接引语是The history teacher told them that the Chinese Communist Party was founded on July 1st,1921
这题后面部分 为什么不是 had founded呢?因为课本上说如果直接引语是过去时,那变间接引语是就要把过去时变成过去完成时的