-- They are surprised at ___ i have told them. -- Really?

问题描述:

-- They are surprised at ___ i have told them. -- Really?
A. thatB. which C. all thatD. all

C
all that= what:the thing(that.) .的事/物
同时作at的介词宾语和told的直接宾语.请问;为什么填B不对呢。 which 在定语从句中作宾语,指代物。根据成分分析:必须同时作两个成分,而which 没此功能。