it wasn't such a good dinner as she had promised us.

这根本不是她许诺给我们的那样好的晚餐
as 表示向她许诺的一样
as引导的方式状语从句
作"像"、"按照……的方式"解.如:
You must do everything as I do.你必须要照我的样子去做.
She stayed in bed as the doctor had told her.她依照医生的吩咐卧床休息.
Leave it as it is.把它维持原状好了.
that 无法表示 像.一样的意思.