Detailed Instructions: Indicate a text span in the passage about which an inquisitive question is asked. (note, don't answer the question).
Q: Sentence: The U . S . and Canada , which do more trade than any other pair of nations , are to meet next month to arrange an acceleration of planned tariff cuts under the U . S . - Canada free trade agreement .<sep>Question: who is the second biggest pair?
A:
than any other pair of nations , are to meet