Đáp án tham khảo, có thể sai: 1b, 2c, 3a, 4a, 5b, 6c, 7d, 8a, 9d, 10b, 11b, 12b, 13b, 14c, 15b, 16c, 17a, 18a, 19b, 20b, 21b, 22a, 23b, 24e, 25d, 26c, 27b, 28a, 29a, 30d, 31b, 32d, 33b, 34c, 35c, 36b, 37a, 38d, 39d, 40a, 41b, 42a, 43a, 44b, 45d, 46c, 47c, 48b, 49a, 50b, source ...