Stephen Hawking believes that the earth is unlikely to be the only planet_____life has developed gradually.

问题描述:

Stephen Hawking believes that the earth is unlikely to be the only planet_____life has developed gradually.
A.thatB.whereC.whichD.whose
选B 解释

实际上是life has developed on the planet,但是在题目中没有on这个词,所以空格中应该填 on which=where