On Earth, among the surest indications of sunspot cycles are believed to be the rate that trees grow, as seen in the rings visible in the cross sections of their trunks.
GWD-10-Q37:GWD-11-26 On Earth, among the surest indications of sunspot cycles are believed to be the rate that trees grow, as seen in the rings visible in the cross sections of their trunks.
A. On Earth, among the surest indications of sunspot cycles are believed to be the rate that trees grow B. On Earth, among the surest indications of sunspot cycles are, it is believed, the rate of tree growth C. On Earth, the rate at which trees grow is believed to be among the surest indications of sunspot cycles D. Among the surest indications on Earth of sunspot cycles, believed to be the tree growth rate E. Among the surest indications on Earth of sunspot cycles is believed to be the rate at which trees grow
answer 是E,why not C?我的困惑在as seen 上,这个 as seen是什么意思,又省略了什么成分呢?谢谢!