题目

More than 10,000 people were made homeless in Ternang when the Sungai Mas overflowed its banks yesterday after six days of continuous heavy rain. The wooden bridges across the river had been swept away. The town is cut off by floodwaters. At the fifth mile, Jalan Tengkn, the water is now two metres deep. It is closed to all traffic. Flood first appeared at mid­afternoon yesterday along the riverbanks. People struggling to higher ground were just in time to escape the destroying of the flood. Most of the flood victims had to leave all their things behind. The news was reported to the National 设{an}是等比数列，有下列四个命题：①an2是等比数列；②anan+1是等比数列；③是等比数列；④lg|an|是等比数列．其中正确命题的个数是A.1B.2C.3D.4