Present simple
Habits, facts, and how things usually are. To say no or ask, add do or does: I don't understand, he doesn't understand.
- I / you / we / they understand
- he / she / it understands
comprendre
Irregular verb.
Like stand
This verb conjugates like stand: understood, understood.
A state, not an action
understand usually describes a state, so it rarely takes the -ing tenses: I understand, not I’m understanding.
In speech, the helping verbs shorten: I’m, he’s, we’re, I’ve, I’ll, I’d.
Enough to talk about now, the past, and your plans, and to give instructions.
Habits, facts, and how things usually are. To say no or ask, add do or does: I don't understand, he doesn't understand.
What is happening now, and plans already arranged: we’re leaving tomorrow.
A finished action at a past time: yesterday, in 2020. To say no or ask, add did: I didn't understand.
Plans and intentions, and what you can see coming: it’s going to rain.
Orders, advice, and instructions. Let’s suggests doing it together. To say no: don't understand.