Grammar · 语法 yǔfǎ

一下

yíxià

The little word that makes a verb brief and friendly: how verb + 一下 turns a bare command into a casual request, where the object goes, how it overlaps with verb reduplication, and how it differs from the time-word 一会儿.

~4 min read

字源 zìyuán Etymology & Structure

字源洞见 zìyuán dòngjiàn · Etymological Insight

一 yī is "one," and 下 xià is "down, below," but here 下 works as a verbal measure word, a count of times an action occurs, like "a stroke, a go": 打了三下 ("struck three times"). So 一下 is literally "one go, one stroke," a single brief instance of the action. From counting one occurrence it softened into the casual "have a quick…" we use today.

Note the tone sandhi: 一 is first tone (yī) in isolation, but before the fourth-tone 下 (xià) it shifts to second tone, yí, by the regular 一 rule, giving yíxià. The measure-word 下 still counts blows and beats elsewhere (敲两下门, "knock twice on the door"), and that counting sense is the seed of the softener: one light touch of the verb.

一下 yíxià The Softener

动词 + 一下 dòngcí + yíxià verb + 一下 — do briefly / casually

动量词 dòngliàngcí · verbal measure

Placed right after the verb, 一下 makes the action quick, light, and informal: 看一下 ("have a look"), 想一下 ("think for a sec"), 试一下 ("give it a go"). It softens commands into friendly requests and lowers the stakes of an action. With most verbs it is the smoothest everyday way to say "just briefly do this."

你看一下这个。

Nǐ kàn yíxià zhège.

Have a look at this.

请等一下。

Qǐng děng yíxià.

Please wait a moment.

我休息一下就来。

Wǒ xiūxi yíxià jiù lái.

I'll rest for a sec and come right over.

用法 yòngfǎ Patterns — Objects, Requests, Sudden Change

一下 in use · the core patterns Verb + 一下 , 等一下 · wait a sec
Verb + 一下 + Object , 看一下手机 · glance at the phone
Verb + 一下 / Verb + Object + 一下 , 帮我一下 · give me a hand
请 + Verb + 一下 , 请说一下 · please say a word about it (polite)
一下子 , all at once; suddenly (adverbial, different sense)

帮我一下 bāng wǒ yíxià give me a hand; help me out

A model of 一下 as a politeness softener. The bare 帮我 ("help me") is blunt; adding 一下 frames it as a small, quick favor and sounds far friendlier. Note that 一下 can follow the object here (帮我一下) because 帮 takes a person directly. The same softening works across requests: 看一下, 等一下, 问一下.

不好意思，能帮我一下吗？

Bù hǎoyìsi, néng bāng wǒ yíxià ma?

Excuse me, could you give me a hand?

一下子 yíxiàzi all at once; suddenly

A related but distinct adverb: 一下子 means "all at once, in one go, suddenly," describing rapid or abrupt change rather than softening a verb: 天一下子黑了 ("the sky went dark all at once"). Do not confuse it with the verb-softening 一下: 看一下 ("have a look") versus 一下子看完了 ("finished reading it in one go").

他一下子就明白了。

Tā yíxiàzi jiù míngbai le.

He understood all at once.

辨析 biànxī 一下 vs. Reduplication vs. 一会儿

辨析 biànxī · Distinguishing the Words

Chinese has two main ways to make a verb brief and casual, and 一下 is one of them. The other is reduplication: doubling the verb, 看看 ("have a look"), 想想 ("think it over"), 试试 ("give it a try"). For single-syllable verbs the two are nearly interchangeable: 看一下 and 看看 both mean "take a quick look." 一下 works cleanly with an object (看一下这本书) and with two-syllable verbs (休息一下), while reduplication is especially at home with short, single-syllable verbs in casual speech.

Quite separate is 一会儿 yíhuìr, which looks similar but does a different job. 一下 is a verbal-quantity word that softens the action ("once, briefly"); 一会儿 is a time-word naming a span ("a little while"). Compare 等一下 ("hold on a sec," the brief act of waiting) with 等一会儿 ("wait a while," the stretch of time you spend waiting). When the point is the action's lightness, reach for 一下 or reduplication; when the point is how long, reach for 一会儿.

成语 chéngyǔ Set Phrases

一举两得 yì jǔ liǎng dé to gain two things in one move Literally "one action, two gains," to accomplish two ends with a single effort, the Chinese "two birds with one stone." 一举 ("one move") echoes the single-instance sense behind 一下: one stroke that yields double the result.

一目了然 yí mù liǎo rán clear at a single glance Literally "one eye, and all is clear," so obvious that a single look takes it in. The spirit of 看一下 raised to perfection: one brief glance suffices. Used to praise a layout, chart, or explanation that is instantly understandable.

一蹴而就 yí cù ér jiù to succeed in one step Literally "one stamp of the foot and it is done," to accomplish something in a single easy stroke. Most often used in the negative, to warn that hard things cannot be done all at once: 学语言不能一蹴而就 ("you can't master a language in one go"). The single-action 一 again, the cousin of 一下子.