onion是可数名词

Cut the onion into paper-thin slices

把洋葱切成极薄的薄片。

Put the onions and ginger in the oven and let them roast for thirty minutes.

将洋葱和姜放进烤箱烘烤30分钟。

Store onions in a cool dry place.

把洋葱头存放在凉爽干燥的地方。