| 谢谢两位, 我再好好体会 hs 的意思, 关于 double 强调动作非常有道理, 逻辑上有问题.
不过, 对于 doubling .....的语法功能, 我有异义, 觉得应该是分词短语作为整个句子的伴随壮语. 此题我曾经毫不犹豫地选A, 因为OG上有类似doubling 的用法, 现在看了HS 的分析, 觉得两题还是有差异的. OG 如下:
49. The cameras of the Voyager II spacecraft detected six small, previously unseen moons circling Uranus, which doubles to twelve the number of satellites now known as orbiting the distant planet.
(A) which doubles to twelve the number of satellites now known as orbiting
(B) doubling to twelve the number of satellites now known to orbit
(C) which doubles to twelve the number of satellites now known in orbit around
(D) doubling to twelve the number of satellites now known as orbiting（B）
(E) which doubles to twelve the number of satellites now known that orbit
The pronoun which should be used to refer to a previously mentioned noun, not to the idea expressed in an entire clause. In A, C, and E, which seems to refer to a vague concept involving the detection of moons, but there is no specific noun, such as detection, to which it can refer. Also in E, the use of the phrasing the number... now known that orbit is ungrammatical and unclear. B and D use the correct participial form, doubling, to modify the preceding clause, but D, like A, uses known as orbiting rather than known to orbit, a phrase that is more idiomatic in context. B, therefore, is the best answer.ffice ffice" /> | 
