1. เปลี่ยน - to change, replace, convert, alter, swap... I'm not sure what exact shades of meaning some of these words convey. "Change" for example, in Chinese can have so many different synonyms, but they're not ACTUALLY synonyms. They're words like "become" "alter" "modify" "change (composition)" and so on. They'll use a series of characters interchangeably, so 變成， 成為， 變化， 改變 use some similar characters in different combinations to create different meanings, but thankfully Thai seems to have those same monosyllabic tendencies.
2. วิธี - way, method.