Sparingly means doing something in small amounts, on purpose, because too much would be wrong. It answers the question how much? — and the answer is always: less than you might expect. It is an adverb, so it attaches to a verb, and it almost always sits after the verb it modifies: use it sparingly, apply sparingly, eat sparingly, spend sparingly. That phrase use sparingly is by far the most common thing you will meet, and you will meet it constantly — on medicine tubes, in recipes, in instructions of every kind. The deliberateness is what makes this word what it is. If you eat sparingly, you are choosing small portions, not starving. If a writer uses adjectives sparingly, that is a compliment: it means the adjectives are chosen, not sprinkled. The word carries a quiet approval of restraint, which is why it turns up so much in advice. Some common company it keeps: use sparingly, apply sparingly, eat/drink sparingly, spend sparingly, give sparingly, and in careful writing, sparingly used, sparingly applied. In instructions you will often see it alone as a whole sentence — "Apply sparingly." Register: a bit more formal than ordinary conversation. Speaking, most people say "don't use much" or "just a little". Written, sparingly is the natural choice. It is also more common than its adjective sparing, which is unusual for an -ly word — normally the adjective wins. One honest complication: the adverb and the adjective mean the same thing, and English does not draw any line between them beyond grammar. So the whole question with this word is where it goes in the sentence, not what it means.

少量地、節制地（刻意少用）。藥膏、保養品、食譜上的 Use sparingly 就是「少量使用」「酌量使用」的意思。