题目

One thing that British and Chinese cultures share is a love for fine tea. Today, when we think of Western tea culture, we often think of the English and beautiful china tea cups. Afternoon tea     People believe that an English lady, Anna, first introduced the idea of afternoon tea. In the 18th and 19th centuries, the English ate only two main meals each day: breakfast and a heavy supper that would last for several hours in the evening. As a result, people often got very hungry during the long wait between these two meals. To solve this problem, Anna came up with the clever idea of i将函数的图象上各点的横坐标伸长到原来的2倍(纵坐标不变)，再     向左平移个单位，所得函数图象的一条对称轴为（      ）.（  科网     (A)     (B)    (c)     (D)