题目

Tristan da Cunha, a 38 –square –mile island, is the farthest inhabited island in the world, according to the Guinness Book of Records. It is 1,510 miles southwest of its nearest, St. Helena, and I, 950 miles west of Africa. Discovered by the Portuguese admiral (上将) of the same name in 1506, and settled in 1810, the island belongs to Great Britain and has a population of a few hundred.                     Coming in a close second –and often wrongly mentioned as the most distant land –is Easter Island, which lies 1,260 miles east of its nearest neighbor, Pi已经一组函数y＝2sin(ωx＋j)(ω＞0，0＜j≤2π)，其中在集合中任取一个数，j在集合{，，，π，，，2π}中任取一个数.从这些函数中任意抽取两个，其图象能经过相同的平移后得到函数y＝2sinωx的图象的概率是         (     ) A．    B．      C．  D．