Because Thai has no tenses the phrase "I am going home" becomes "I go home" which is "Pom bai bahn" (or "Dichan bai bahn" if you are female).

The same phrase can also mean "I went home" or "I will go home" etc. The tense can only be understood from the context and the addition of 'time words'. Thus to convey a past tense a Thai will say something like "I go home, already" which is "Pom bai bahn lairo" or a future action "I will go home tomorrow" which is "Pom bai bahn proong nee".

The example of the Chinese for train is a similar system to Thai. They have a word for all forms of transport which is "rot" which means something like "vehicle". A train is "rot fai" literaly "vehicle fire".

Jon