I agree with Saename.
I would also point out that WTBTS only uses verse 9 and 10, but conveniently skips verse 8. Verse 8 is VERY important.
"When he took the scroll, the four living creatures and the 24 elders fell down before the Lamb, and each one had a harp and golden bowls that were full of incense. (The incense means the prayers of the holy ones.)"
WTBTS teaches that the 24 elders ARE the 144,000. However, verse 10 says, "and you made them to be a kingdom and priests to our God." The four living creatures and the 24 elders are not talking about themselves, but some other group.
Verse 9 also is important. "And they sing a new song, saying: You are worthy to take the scroll and open its seals, for you were slaughtered and with your blood you bought people for God out of every tribe and tongue and people and nation,"
There's two points here:
1. "They sing a new song" - This seems like it would be the 144,000 because they too sing a new song. But, wait! There's a key difference. Rev 14:3 says: "And they are singing what seems to be a new song before the throne and before the four living creatures and the elders, and no one was able to master that song except the 144,000, who have been bought from the earth." So, here you have the four living creatures and the 24 elders in Rev 5:8 singing, but in Revelation 14, it's the 144,000 who are singing BEFORE the four living creatures and elders. AND it's only the 144,000 who could master that song. This means that the song sung in Revelation 5 is NOT the same song sung by the 144,000.
2. Where are the 144,000 taken from? From the 12 tribes of Israel, 12,000 from each. Where do the great crowd come from? From all nations and tribes and peoples and tongues.
Incidentally, the Kingdom Interlinear has a chart in the opening cover.