1. In the conversion of saliva into poison, one might suppose that a fixed process took place.
    人们可能认为，唾液转变成毒液，其中有固定的程序。

2. It is not a simple competition for a fixed amount of food determined by the physical environment, because the environment that determines our evolution is no longer essentially physical.
    它已不是为争得物质环境所决定的东西所决定。