Editing Spanish grammar (section)

=== Present progressive and imperfect progressive ===
The present and imperfect progressive both are used to express ongoing, progressive action in the present and past, respectively. For example:
* {{lang|es|Estoy haciendo mi tarea.}} (I am doing my homework)
* {{lang|es|Estamos estudiando.}} (We are studying)
* {{lang|es|Estaba escuchando la radio.}} (I was listening to the radio)
* {{lang|es|Él estaba limpiando su cuarto.}} (He was cleaning his room)
The present progressive is formed by first conjugating the verb {{lang|es|italic=yes|estar}} or {{lang|es|italic=yes|seguir}}, depending on context, to agree with the subject, and then attaching a gerund of the verb that follows. The past (imperfect) progressive simply requires the {{lang|es|italic=yes|estar}} or {{lang|es|italic=yes|seguir}} to be conjugated, depending on context, in imperfect, with respect to the subject.

==== Forming gerunds ====
To form the gerund of an {{lang|es|italic=yes|-ar}} verb, replace the {{lang|es|italic=yes|-ar}} of the infinitive with {{lang|es|italic=yes|-ando}};
e.g. {{lang|es|italic=yes|jugar}}, {{lang|es|italic=yes|hablar}}, {{lang|es|italic=yes|caminar}} → {{lang|es|italic=yes|jugando}}, {{lang|es|italic=yes|hablando}}, {{lang|es|italic=yes|caminando}}.
For {{lang|es|italic=yes|-er}} or {{lang|es|italic=yes|-ir}} verbs, replace the {{lang|es|italic=yes|-er}} or {{lang|es|italic=yes|-ir}} ending with {{lang|es|italic=yes|-iendo}};
e.g. {{lang|es|italic=yes|comer}}, {{lang|es|italic=yes|escribir}}, {{lang|es|italic=yes|dormir}} → {{lang|es|italic=yes|comiendo}}, {{lang|es|italic=yes|escribiendo}}, {{lang|es|italic=yes|durmiendo}} (note that {{lang|es|italic=yes|dormir}} undergoes the stem vowel change that is typical of {{lang|es|italic=yes|-ir}} verbs).<!--It is arguably not irregular for an ''-ir'' verb to raise its stem vowel.-->
In {{lang|es|italic=yes|-er}} verbs (and some -ir verbs, like disminuir) whose stem ends with a vowel, the {{lang|es|italic=yes|i}} of the {{lang|es|italic=yes|-iendo}} ending is replaced by {{lang|es|italic=yes|y}}: e.g. {{lang|es|italic=yes|leer}}, {{lang|es|italic=yes|traer}}, {{lang|es|italic=yes|creer}} → {{lang|es|italic=yes|leyendo}}, {{lang|es|italic=yes|trayendo}}, {{lang|es|italic=yes|creyendo}}.
In {{lang|es|italic=yes|-ir}} verbs whose stem ends with {{lang|es|italic=yes|e}}—such as {{lang|es|italic=yes|reír}} and {{lang|es|italic=yes|sonreír}}—the stem vowel {{lang|es|italic=yes|e}} is raised to {{lang|es|italic=yes|i}} (as is typical of {{lang|es|italic=yes|-ir}} verbs), and this {{lang|es|italic=yes|i}} merges with the {{lang|es|italic=yes|i}} of the {{lang|es|italic=yes|-iendo}} ending; e.g. {{lang|es|italic=yes|reír}}, {{lang|es|italic=yes|freír}} → {{lang|es|italic=yes|riendo}}, {{lang|es|italic=yes|friendo}}.