Chinese phrase
开封后多长时间内要用？ kāi fēng hòu duō cháng shí jiān nèi yào yòng
Meaning
How long is it good for after opening?
When to use it
Asks how long a product remains usable after opening. It is a practical, neutral question about the recommended period for using food, medicine, cosmetics, or other products.
Example dialogue
我这瓶面霜开封后多长时间内要用？ wǒ zhè píng miàn shuāng kāi fēng hòu duō cháng shí jiān nèi yào yòng
How long is this bottle of face cream good for after opening?
一般建议六个月内用完，超过可能影响效果。 yì bān jiàn yì liù gè yuè nèi yòng wán chāo guò kě néng yíng xiǎng xiào guǒ
It is generally recommended that you finish it within six months, since it may be less effective after that.