you can see from here the museum--we visited this afternoon.

A that.这道题是考察定语从句的用法,we visited this afternoon是修饰museum的定于从句,从句缺visited的宾语.主句不缺成分.that 指示代词,在从句中可作宾语.where 指示副词,在从句中作状语.what 在主句和从句中都充当成分.as 连词.