Stemming can generally help improve retrieval performance in English text, but it may not always be the case. Choose one of the three choices: stemming or no stemming or maybe stemming, for each of the following 4 cases. You need to provide the reasons/explanations for each of your choices.

1. When the corpus is small and users care more about precision

2. When the corpus is small and users care more about recall

3. When the corpus is large and users care more about precision

4. When the corpus is large and users care more about recall