The words 常常 and 往往 can both be translated as 'often', but their usage isn't quite the same.
Here's a quick guide to the situations in which 常常 and 往往 should be used.
常常 (cháng cháng)
常常 is a general-purpose word for 'often' or 'frequently'. Pretty much any situation that can be described with 'often' in English can be described with 常常 in Mandarin.
常常 can be used for past, present, future or conditional events. It can also be used for hypothetical events.
Note that the negative of 常常 is usually just 不常.
wǒ chángcháng kàn shū.
I often read books.
wǒ dìdi xiǎo de shíhòu, wǒ chángcháng dài tā qù gōngyuán.
When my brother was young, I often used to take him to the park.
yàoshi wǒ yǒu qián dehuà, wǒ huì chángcháng chūqù wánr.
If I had the money, I would often go out and have fun.
wǒ yī yǒu xiǎogǒu, jiù huì kāishǐ chángcháng sànbù.
As soon as I have a dog, I'll start going for walks frequently.
tā shì ge hěn shí zài de rén, tā chángcháng huì bǎ péngyou de qìchē xiū hǎo.
As she's a very practical person, she often fixes her friends' cars.
However, this last sentence could use 往往.
往往 (wǎng wǎng)
往往 is also used to indicate frequency, but must appear with a reason or condition that causes the event to occur frequently. It can't just appear in a simple statement that something often happens. 往往 can be used for present events, but is most commonly used for past events. It cannot be used for future, conditional or hypothetical events.
tā bù tài néng hē jiǔ, dànshì péngyou dōu xǐhuān hē, suǒyǐ tā wǎngwǎng hēzuì le.
He's not a big drinker, but his friends all like to drink, so he often gets drunk.
yīnwèi tǐyùchǎng lí wǒ jiā bù yuǎn, wǒ wǎngwǎng qù kàn zúqiúsài.
As the stadium isn't far from my house, I often go and watch football matches.
xiǎo lǐ shīmián wǎngwǎng shì yīnwèi tā de línjū lǎoshi dà shēng chǎojià.
Xiaoli often loses sleep because his neighbours are always arguing loudly.
Note that a sentence with 往往 doesn't necessarily need 因为 or 所以. It just needs to include a reason for the frequency of the event.
zhè jiā fànguǎn xiàwǔ de shíhòu wǎngwǎng méiyǒu hěn duō gùkè.
In the afternoon, this restaurant doesn't often have a lot of customers.
Translated from: eastasiastudent
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