El profesor espera que ustedes sean siempre puntuales.
The teacher expects you to always be punctual.
Breakdown of El profesor espera que ustedes sean siempre puntuales.
ser
to be
el profesor
the teacher
ustedes
you (plural)
siempre
always
Questions & Answers about El profesor espera que ustedes sean siempre puntuales.
Why is the verb sean used here instead of son?
Because the teacher is expressing an expectation for other people (ustedes). When we use verbs of desire or expectation like esperar que (to hope/expect that) or querer que (to want that) followed by a new subject, the second verb must be in the subjunctive mood. sean is the subjunctive form of ser.
Which verb does sean come from, and how is it formed?
sean is the present subjunctive form of ser (to be) for ustedes. The verb ser is irregular. Normally, to make the subjunctive, you take the 'yo' form of the present tense, drop the 'o', and add the opposite ending. But since the 'yo' form of ser is soy (it doesn't end in 'o'), it uses a completely irregular subjunctive stem: sea-.
Why does esperar mean 'expects' here instead of 'waits'?
The verb esperar can mean to wait, to hope, or to expect. When it is followed by que and a change of subject (like the teacher expecting something of you all), it usually translates to 'hopes that' or 'expects that'. In the context of a classroom rule about being on time, 'expects' is the most natural translation.
Why does puntuales end in '-es'?