### 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 you will definitely ask: Why is the shelf life of bags one year, while the shelf life of cans is two years or more?
### Errors: There is a major error of incorrect translation has stylistic problems at "While the shelf life of bags is one year, the shelf life of cans is two years or more.". There is a minor error of incorrect translation includes information not present in the correct translation at "definitely".

### 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?