### 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 everyone must ask: Why is the shelf life of the bag is one year, and the shelf life of the can is two years or more?
### Errors: There is a major error of problems with grammar, other than orthography at "the bag and the can". There is a major error of incorrect translation includes information not present in the correct translation at "So everyone must ask". There is a major error of incorrect translation has stylistic problems at "Why is the shelf life of the bag is one year, and the shelf life of the can is two years or more?".

### 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?