General Hopkins has died. [1] He never recovered [2] from that last operation.
We made [3] a reservation for a twin-bedded room. We hope the hotel has received [4] our letter.
[1] Present perfect shows current relevance to the flag at half-mast. At the present moment the general is dead. That explains the flag situation just now.
[2] His failure to recover happened entirely in the past, not within a time period which includes the present.
[3] (After reading the second part, you realize that "made" really means "wrote to the hotel to see if a reservation was available".) Writing to the hotel and sending the letter happened entirely in the past, not within a time period which includes the present.
[4] Our hope is a present hope that at this time, as we speak, the letter is now at its destination. The receiving of our letter is hoped to be at any time after we sent it all the way up to and including the present moment.
By contextualizing the sample sentences in other ways, you may be able to argue for other choices of tense, but I believe the test makers would prefer the answers I showed above.