For some time now, world leaders _____ out the necessity for agreement on climate change, the world economy and African development．

A．had been pointing

B．have been pointing

C．were pointing

D．pointed

53～55题共用题干）水库边放养和饲喂生鱼的散养猪中，部分猪发病，主要表现为消化不良、下痢、贫血、水肿、消瘦，胆管和胆囊发炎，有黄疸症状，后期肝硬化并出现腹水。

最有可能感染的寄生虫是

A．华枝睾吸虫

B．日本血吸虫

C．卫氏并殖吸虫

D．布氏姜片吸虫

E．程氏东毕吸虫