### Chinese: 那么大家肯定会问：为什么袋装保质期是一年，而听装的保质期是两年或更长呢？
### English: Then people will surely ask: Why is the shelf life of the bagged milk powder one year, while the shelf life of the listened milk powder is two years or longer?
### Errors: There is a major error of incorrect translation has stylistic problems at "people will surely ask". There is a major error of incorrect translation includes information not present in the correct translation at "listened milk powder". There is a minor error of incorrect translation is missing content from the correct translation at "the bagged milk powder".

### Improved English: Then you may ask: why is the shelf life of milk powder one year in bags and two years or longer in cans?