IMPERATIVE: THE -U ENDING
The -u ending is used when ordering/ inviting someone else to do something or when telling or suggesting to ourselves what to do!
IMPERATIVE + INFINITIVE
An imperative may be followed by an infinitive:
Bonvolu manĝi! Please eat!
(NOT: Bonvolu manĝu. Do not use two imperatives one after the other in that way).
QUESTIONS WITH -U
In questions, the -u ending generally means "shall":
Ĉu ni iru? Shall we go?
Ĉu mi legu tiun libron? Shall I read that book?
THE -U ENDING IN SUBORDINATE PHRASES
We also use the -u ending in subordinate phrases (clauses) starting with ke, when the verb in the preceding, main part of the sentence expresses a want, desire, demand or preference:
This grammatical usage is also called the "subjunctive".