5. Do you have this in stock?
这个还有存货吗？
还能这样说：
Is there any of this in stock?
Is there any more of this in the storeroom?
应用解析：
have... in stocks 持有……公债券；
lay in a stock of 储备……；储存……；
stocks and stones 无生命之物；木石；死气沉沉的人
6. Do you have this in yellow?
这种有黄色的吗？
还能这样说：
Do you have yellow ones?
Do you have anything yellow of this style here?
应用解析：
as yellow as a crow's foot 色黄如金；
sand yellow 砂黄；沙黄色；
a yellow streak 生性怯懦；
yellow card （足球等运动中的）黄牌，黄卡
7. Do you have any on sale?
你们有什么特卖品吗？
还能这样说：
Is ther anything on sale?
Do you have some articles on sale?
应用解析：
for sale 待售（通常由物主或代理人经手）；
例如：She has put her house up for sale.
她的房子现在出售。
8. What's the current best seller?
现在什么是最畅销的？
还能这样说：
Which brand do you sell the most?
What's the best current selling?
应用解析：
seller 售出之物（尤指以修饰词语描述之方式出售）；
seller's market 卖方市场（供不应求而有利卖方的）