单项选择题
Questions 8 to 10 are based on the following conversation. At the end of the conversation, you will be given 15 seconds to answer the questions. Now listen to the conversation.
Which of the following is NOT mentioned about the single-lens reflex? （）
A．Different lenses can be used.
B．Focusing is easier.
C．You can see what you are taking.
D．It is cheaper and lighter.