请教og12-14 和73的平行结构时态问题

FindNeverland

og12-14:Sunpots,vortices of gas associated with strong electromagnetic activity, are visible as dark spots on the surface of the Sun but have never been sighted on the Sun's poles or equator.

这里的but前后时态可以不一致

og12－73：Combining enormous physical strength with higher intelligence,the Neanderthals appear as equipped for facing any obstacle the environment could put in their path,but their relatively sudden disappearance during the Paleolithic era indicates that an inability to adapt to some environmental change led to their extinction.

og D中的解释： Present-tense appear is needed to parallel Present-tense indicates

EvaCheng

是说时态不一定需要相同了？？？？？时态一致和时态一样有什么不一样的？？？？？？？？

zhengqingku

平行结构的用法

wanghongl

补充一点，“时态一致”不是时态一样

james2201

你上面说的这道题，but前面说的是：太阳黑子，……，被人们观测到是太阳表面的黑点。这是一个科学事实，我们知道，科学事实是要用一般现在时的。

而but后面讲的是：太阳黑子，……，至今为止（从过去到现在）没有在太阳的两极和赤道被观测到。所以这里要用现在完成时。

这样分析后，其它选项的时态不符合逻辑。

我想，所谓的“一致”是指结构一致，而不是时态一致。