1. We don't know where we should put the sofa.
 We don't know where to put the sofa.
2. The rules didn't specify who I should speak to in case of an emergency.
The rules didn't specify who to speak to in case of an emergency.  
3. Mai wondered how she could ride the scooter.
Mai wondered how to ride the scooter.
4. Let us decide when we should start the project.
Let us decide when to start the project.
5. Could you tell me where I can find a good hotel?
Could you tell me where to find a good hotel?
6. We must find out what we are to do next.
We must find out what to do next.
7. A good dictionary tells you how you should pronounce the words.
A good dictionary tells you how to pronounce the words. 
8. We are not sure who we will meet at the entrance.
We are not sure who we will meet at the entrance.