並前往https://books.google.com.tw/books?id=3opIxHlHtukC&pg=PA68&lpg=PA68&dq=dual&source=bl&ots=hjx7wF8ZNs&sig=ACfU3U1vuk5vO-FK1ZHpwF2JMVWrTzte8w&hl=zh-TW&sa=X&ved=2ahUKEwjJ6_SN-Lf9AhWtl2oFHR4FAhYQ6AF6BQjxAhAD