I think there are issues on how to read and write (in Thai) English words.

In the case of 'LAB' and 'LAP': 'LAB' is commonly read (in English) like "แหล็บ" and written (in Thai) as "แล็บ". Why?

In English words ending with "B" or "D" are usually read with "LOW" pitch/accent. For examples: garb, grab, band, hand, lanb, land, robe, sand, slab, stand, tomb, womb,...

And word ending with "P" or "T" are usually read with "HIGH" pitch/accent. For examples: carp, crap, rap, map, lamp, rope, slant, slap, stamp, stunt, want,...

How we write these words in Thai without regard to how they read or sound in English can be a source of confusion and an obstacle for learning English!