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