雑草を取らなくてはならない。

weed

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

to take; to pick up; to harvest; to earn; to win; to choose; to steal; to eat; to have (a meal); to remove (one's glasses, etc.); to compete (in sumo, cards, etc.); to play

if ... then; when; and; why don't you...?; the more (one does something); because; since