晕!大全677的答案居然和OG 11th不一样

OG 11th SC部分第9题给的答案竟然不是C,大家猜猜答案是哪个? 看来大全的答案还不是完全正确的.同样在CR大全上面,也发现与OG 11th不一样答案的题.呵呵,ETS...

677.    Sunspots, 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.

(A) are visible as dark spots on the surface of the Sun but have never been sighted on

(B) are visible as dark spots that never have been sighted on the surface of the Sun

(C) appear on the surface of the Sun as dark spots although never sighted at

(D) appear as dark spots on the surface of the Sun, although never having been sighted at（C）

(E) appear as dark spots on the Sun’s surface, which have never been sighted on

A就很好了。

你连OG11都有了，真快

This one is quite tricky. on the equator is the correct idiom so B, C and D can be ruled out. which clause in Choice E makes this choice disqualified. The last one that is still standing there is Choice A.  

C:Although typically introduces a subordinate clause, which has a subject and a verb, but here there is no subject and sighted is not a complete verb

晕,这也能错,大全还有没有权威性?