Co ba cach phat am "ed":
- [id]: khi theo sau am 't' hoac 'd'.
eg: wanted, needed, added, divided, depended,...
- [t] : khi theo sau mot trong nhung am [p,k,f,s(ngan),s(dai),ch]
eg: watched, stopped, laughed, impressed,...
- [d]: khi khong thuoc 2 nhom tren.
eg: seemed, arived, studied,...
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