It’s partially true. You cannot directly combine/merge two partitions (there’s actually a good reason for this but we can discuss that later). There is a trick involved for combining the two partitions using Partition Magic (or similar utility).
You first need to delete one of the partitions (usually not the primary C: one for obvious reasons). So, in the case of the TR2s, that would be partition D: and E:. Of course, you want to make sure you have any data on these partitions backed up somewhere just in case.
Once the partitions are deleted, free space is created on the hard disk. At this point, you can then add this free space to your existing partition (C:) and make it the full size of the disk (~38GB or something like that).