It looks like the text explains how a purpose clause introduced by "so that" can be replaced with other phrases like "prevent/avoid + V-ing" or "allow/enable/let/make + object + infinitive" or "in case."

Here’s a summary of how the examples can be transformed:

1. **Original**: He killed the man who helped him bury the treasure so that nobody but himself would know where it was.
**Replaced**: He killed the man who helped him bury the treasure in order to prevent anyone knowing where...

2. **Original**: Don’t let him play with scissors so that he may cut himself.
**Replaced**: Don’t let him play with scissors in case he cuts himself.

3. **Original**: They talked in whispers so that they didn’t want me to overhear them.
**Replaced**: They talked in whispers to avoid me overhearing them.

4. **Original**: Please shut the gate so that I don’t want the cow to get out of the field.
**Replaced**: Please shut the gate to prevent the cow from getting out of the field.

5. **Original**: I am putting the nets over my strawberry plants so that I don’t want the birds to eat all the strawberries.
**Replaced**: I am putting the nets over my strawberry plants to prevent birds from eating all the strawberries.

These transformations express the same intent while varying the structure of the sentences.