however,for those in situation------these two optians are not available 填where因为【situation】在从句中作状语【these two optians are not available in this situation】,所以用wherethat是做主语和宾语的...可是我还想问同位语从句中that与where的区别，他们好像用法很相似，that引导的同位语从句可不可以改为where,满烦你列举一些你上面的这句是一句定语从句先行词是【situation】同位语从句的话The situation that the weather in London is changeable is within our consideration