A Chinese verb never changes — 吃 is always 吃, and the timing rides on add-ons like 了 / 过 / 正在 / 明天. English is the opposite: the timestamp is welded onto the verb — eat / ate / am eating / have eaten — and you can't open your mouth without picking one. So step one of speaking English is deciding: when did this happen, and from what point of view am I telling it?