### 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: So you're sure to ask: Why is the shelf life one year for bags and two years or more for cans?
### Errors: There is a major error of wrong grammatical register (eg, inappropriately informal pronouns). internal inconsistency (not related to terminology) at "So you're sure to ask". There is a minor error of incorrect translation includes information not present in the correct translation at "you're sure to ask".

### 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?