The recent discovery of the existence of a far greater number of planets than had previously been thought only _____ undergirds the argument for intelligent lifeforms; such an argument depends on more than a mere tally of planets, for only those planets that can form a viable atmosphere can host the conditions necessary for life.
A subtly
B minimally
C obliquely
D retroactively
E discursively
F indirectly
最近的发现:existence of more planets than before
可以证明intelligent lifeforms的:有适合的生命的大气和环境的planets
现在的问题是,最近发现的planets不知道是否是可以供生存的planets,也就是无法直接证明。
所以任何表面可以证明的选项应该都不选,因为及时是轻微的证明也是证明了,所以可以排除AB
看剩下的,D追溯的 E discursively(漫然的?)应该也不能选因为明显没关系