How many times has Bob been to Canada before? A. never B. once C. twiceĐoạn văn1/97SECTION I: LISTENING Part 1: Questions from 1 to 6. Listen to a conversation about a journey. Choose the correct answer A, B or C for each of the following questions. How many times has Bob been to Canada before? neveroncetwiceGiải thíchChọn A