题目内容：

Stephen Hawking believes that the carts is unlikely to be the only planet ( ) life has developed gradually .
A that B,where C,which D,whose

优质解答

B.where

追问：

why ?可以分析一下吗

追答：

where 作定语从句life has developed gradually 的地点状语，即 life has developed gradually （in the planet）