WQ: Hey KAT! Wow...wait, 我们穿的裤子一样耶！
KAT: OMG! Yeah! We ARE wearing the same thing! Where did you get it?
KAT: Hmm, we usually say that kind of clothing is a must-have item.
WQ: M-u-s-t, must, 是必须的意思，have, h-a-v-e, 拥有，must-have, 必须拥有，就是必备单品喽！
KAT: Exactly! Must-have items often go with many different styles. For example, skinny jeans are a must-have in today's fashion. 紧身牛仔裤是时尚潮人的必备单品。
WQ: That's why we are both wearing it! 对了，我这条裤子买的特值，买一送一呢！
KAT: What? Buy one get one free? That's such a great bargain!
WQ: Buy one get one free? 我猜这就是买一送一的意思吧？
KAT: That's correct! Sometimes you can buy one and get one 50% off. Guess what that means?
WQ: Hmmm, 我想，这就是买一件，第二件打5折，对不对？
KAT: Good job! Besides, many stores are having end of season sales!
WQ: 这个我知道，就是换季大甩卖！Actually, I got these pants from the end of season sale! 我这条裤子就是换季大甩卖的时候买的！
KAT: There you go! I think we should pay a visit to the mall together this weekend, shall we? We can not and must not miss the end of season sale!
WQ: Sounds good!
KAT: It's a date!! Now let's see what you've learned today!
第二，买一送一，可以说: buy one get one free;
第三，换季大甩卖，叫做end of season sale.