Question

We were to have told you,but you were not in.

用were to tell不就可以了么（这是一个选择题），为什么选项要用have told.
I was to have gone on Tuseday.But on that day, I had a terrible cold so I decided to wait till Wednesday.同类型的。
He was to have been here by 7but now it's 9 and there is no sign of him.同类型的。

Answer 1

用to have told。
下面分析为什么用to have told。

We were to have told you,but you were not in。
我们应该早就告诉你，但你那时不在。
to have told 是不定式的完成时，表示“应该已经.......的了”，表示动作已经过去。

We were to tell you,but you were not in.
意思是：我是要（将来）告诉你，但你那时（以前）不在。
to tell表示动作还没发生，表将来发生的动作为。
那这句话就应这样理解：我以后告诉你，但你以前不在。这是什么逻辑？

Answer 2

这句话的意思是：我们本来打算告诉你的，但是你不在。
重点在这个“本来”二字上面，用完成时表示。
如果没有完成时，仅用were to tell，就是我们打算告诉你，但是你不在，没有这层语气了。

Answer 3

用have told表示过去完成时，表示过去已经告诉。have gone 也是一样，表示过去已经去过。