1,These flowers are from Guangdong.He said. He said_that____these flowers ___were____from Guangdong.
2 Light travels faster than sound.My teacher told me.
My teacher told me __that__light ___travels_faster than sound.
3 There will be a meeting in five days.Jack didn't know.
Jack didn't know__that___there __would __ _be__ a meeting in five days.
第2句从句表达的是自然规律,时态保持不变