1. I am just looking around, thanks.
我只是想随便转转，谢谢!
look around ：随便转转
I don’t always buy something. Sometimes I just go and browse.
我不经常买东西，有时我只是走走逛逛。
2. I'd like to try on this sweater.
我很想试一下这件毛衣。
try on ：试穿
3. Sorry to bother you, but could you tell me where the fitting rooms are?
对不起，打扰了，你可否告诉我试衣间在哪里?
fitting rooms ：试衣间
4. Can I sample a strawberry?
我能尝一颗草莓吗?
Sample ：品尝;还有样品，取样的意思
表示品尝的还有 savor taste
Eg: She drank the wine slowly, savoring every drop.
她慢慢地喝着酒，仔细品尝每一滴。
I hope you can taste Beijing Duck someday.
我希望你有机会尝一尝北京烤鸭。
5. That suit looks very good on you.
你穿这个外套很合身。
穿起来很合身： looks good on sb
6. What size shoes do you wear?
你穿多大号的鞋?
问尺寸、号码 what size + 衣服(鞋子、外套等)+ do you wear?
What size do you take?
你要多大的号的?
7. Do you have change for a twenty-dollar bill?
你能换开20美元的钱吗?
change ：兑换，找回的零钱。
Eg：Here is your receipt and change.
这是您的收据和找回的零钱。