in stock的意思是：存货。缺货应表达为：not in stock。
例句：①In answer to your recent inquiry, the book you mention is not in stock.
您近日询问的书暂时无货，谨此奉覆。
②Have you any grey pullovers in stock?
你们有灰色套头毛衣的现货吗？
stock除了名词存货外，还有其它含义：
n.储备；树干；股票；股份；家畜；血统；汤汁；声望。
v.采购；储存；供给；发新芽。
adj.惯用的；存货的。
例句：①We need to replenish our stocks of coal.
我们需要再次补充煤的储备。
②We must stock up with food for the holiday.
我们必须采购一些食品以备假期之需。
③She's tired of her husband's stock jokes.
她已听厌了丈夫那老一套的俏皮话。