单项选择题


Questions 4 to 7 are based on the following conversation. At the end of the conversation, you will be given 20 seconds to answer the questions.
Now listen to the conversation.
What are the speakers mainly discussing

A.An experiment in Antarctica.
B.Part of the Larsen Ice Shelf broke off.
C.The formation of the Larsen Ice Shelf.
D.An expedition in Antarctica.