Sad to say, there are many points in your report we do not agree with, as pointed out by my friend Maria Jones as well.

sad 的意思是"悲伤的"，在这里与 to say 搭配使用表示"遗憾地说"。 to 是不定式符号，与动词 say 连用构成动词不定式 to say（说）。 say 是动词，意思是"说"。 sad to say 是一个固定短语，意思是"遗憾地说"，用于表达对某事的遗憾或失望。