单项选择题
A. In a photographer’s studio. B. In the library. C. In the post office. D. Not mentioned.
A.Two days. B.No more than 3 days. C.At least three days. D.Less than one week.
A.It is not something important. B.The students should already know it. C.It will be explained later in the lecture. D.The students need lo answer his question.