phonetic symbols裡面的/k/是否有兩個讀音?

I think you are referring to whether the /k/ sound is aspirated or not. Pls look at the following words:

sky, scare, scout. They sound a bit like sguy, sgare, sgout.

The /k/ in " sky " is unaspirated whereas the /k/ in " kite " is aspirated. Hence, " discuss " sounds like " disguss " but not " diskuss ", not in the manner as " car " (/kar/) is pronounced.

Similarly the rule applies to " spy ", " spare ", " spout ", " sty ", " stare ", " stout ", etc. where they sound a little like " sby ", " sbare ", " sbout ", " sdy ", " sdare ", " sdout ".

Hope this will be of help to you!