To out emphasis on a small quantity, you can insert one of the following three adverbs: 只(zhǐ), 就 (jiù) and 才(cái), translatable as “only”.
Here are a few examples:
今天上课的人很少，就/只/才十一个人。
jīntiān shàngkè de rén hěn shǎo, jiù/zhǐ/cái shíyī gèrén.
Today there were few in class, only eleven people.
我才/只/就睡了两个小时。
Wǒ cái/zhǐ/jiù shuìle liǎng gè xiǎoshí.
I only slept two hours.
这本书他就看了一遍，不会背的。
Zhè běn shū tājiù kànle yī biàn, bụ̀ huì bèi de.
He only read this book once, he can’t know it by memory.
就, which means “just”, and 才, which means “only just”, are two adverbs frequently used in the Chinese language, more in the written form, than the spoken.
Although they can be translated respectively as “just” and “only just”, their use is much more complex, so we’ll analyze their occurrences in detail, comparing them.
就 is used when a speaker considers that an action takes place quickly, when it happens “soon” or when the time it takes to happen is brief. When it expresses this meaning, you can find 了(le) at the end of the phrase.
Here’s an example:
我从小就喜欢打篮球。
wǒ cóngxiǎo jiù xǐhuan dǎ lánqiú.
I enjoy playing basketball since I was little.
才 is used to signal the recent completion of an action (“just, only now”) or with a restrictive value “only”.
Here’s an example:
我才从重庆回来卡塔尼塞塔不久。
Wǒ cái cóng Chóngqìng huílai kǎ tǎ ní sāi tǎ bùjiǔ.
Not long ago I got back to Caltanissetta from Chongqing.
才 is also used when a speaker considers that an action takes place slowly, when it happens “late” or when it takes a long time to happen. When expressing this meaning, there can never be 了 at the end of the phrase.
Here are a few examples:
演出七点半开始，他七点就到剧场了。 (The action happened “early”)
Yǎnchū qī diǎn bàn kāishǐ, tā qī diǎn jiù dào jùchǎng le.
The show starts at 19:30 and he got to the theater ar 7.
演出七点半开始，他八点才到剧场。(L’azione è avvenuta in “ritardo”)
Yǎnchū qī diǎn bàn kāishǐ, tā bā diǎn cái dào jùchǎng.
The show started at 19:30 and he only got there at 20.
这本书他念了十分钟就会背了。 (It used little time)
Zhè běn shū tā niànle shífēn zhōng jiù huì bèi le.
He read this book out loud for ten minute and already knows how to repeat it.
这本书他念了一个小时才会背。 (It used little time)
Zhè běn shū tā niànle yī gè xiǎoshí cái huì bèi.
He knows how to repeat this book only after reading it out loud for an hour.
就 and 才 can both be used to express two actions or situations that follow each other. 就 expresses that the time between one action / situation and another is brief; 才cái, instead, expresses that the time between one action / situation and another is long. For example:
他刚生病就告诉妈妈了。 (Short time)
Tā gāng shēngbìng jiù gàosu māma le.
As soon as he got sick he told his mom.
他病好了，才告诉他妈妈。 (Short time)
Tā bìng hǎole, cái gàosu tā māma.
He told his mom only after he got better.
她一毕业就回国了。 (Short time)
Tā yī bìyè jiù huíguó le.
He returned to his country right after graduating.
她毕业一个月后，才回国。 (Short time)
Tā bìyè yī gè yuè hòu, cái huíguó.
He returned to his country only a month after he graduated.
The structure “一 (yī) … 就 (jiù) …”
The structure “一 (yī) … 就 (jiù) …” (As soon as…, then…) expresses that two actions immediately follow one after another. For example:
他很聪明，一学就会。
Tā hěn cōngming, yī xué jiù huì.
He is smart. He learns right after studying.
我一下课就去图书馆看书。
Wǒ yị̄xià kè jiù qù túshūguǎn kànshū.
I go to the library to read as soon as class finishes.
我一下课就去图书馆看书了。
Wǒ yị̄xià kè jiù qù túshūguǎn kànshū le.
As soon as class finished I went to the library to read.
天刚亮，我的朋友们就走了。
Tiān gāng liàng, wǒ de péngyou men jiù zǒu le.
My friends left as soon as it was daytime.
When 就 and 才 are found in a phrase that indicates a temporal arc, 就 expresses that the speaker considers that they’re “late”; 才, on the other hand, expresses that the speaker considers that it is “early”.
Here are a few examples:
那天，看完演出，我们到家就九点五十了。 (They returned late)
Nà tiān, kànwán yǎnchū, wǒmen dàojiā jiù jiǔ diǎn wǔshí le.
That day, after seeing the show, we only got back home at 21:50.
那天，看完演出，我们到家才九点五十。 (They returned early)
Nà tiān, kànwán yǎnchū, wǒmen dàojiā cái jiǔ diǎn wǔshí.
That day, after seeing the show, we just got home at 21:50.
To remember the structure:
只要 (zhǐyào) …, 就 (jiù) /便 (biàn) … “So long as…, then…”
Here are a few examples:
只要努力，就会成功。
Zhǐyào nǔlì, jiù huì chénggōng.
So long as you work hard you’ll have success.
只要去中国，就会吃正宗的中国菜。
Zhǐyào qù Zhōngguó, jiù huì chī zhèngzōng de Zhōngguócài.
So long as you go to China, you can eat authentic Chinese food.
As well as the structure:
只有 (zhị̌yǒu) …, 才 (cái) … “only if…, then…”
Here are two examples:
学生只有多听多说多读，才能学会中文。
Xuésheng zhị̌yǒu duō tīng duō shuōduō dú, cáinéng xuéhuì Zhōngwén.
Only if students listen, speak and read more can they learn the Chinese language.
只有坐飞机才能到中国。
Zhị̌yǒu zuò fēijī cáinéng dào Zhōngguó.
You can only go to China by plane.
Photo Credits: 
IMG_6895 1 by Dennis Amith
