Praáctica de gramática #1

- Yo tenía que lesles había escribto una nota y se loa mandoé anoche.

It seems to me that you were trying to say "I had written them a letter and sent it to them last night."

- El estudiante le pintó lasu bicicleta de gris y se loa dio ayer.

"Bicicleta" is a feminine noun, which means you should use "la" as in "se la dio ayer" to refer to it. Also, using "su" instead of "le" and "la" sounds more natural.

- La conductora le limpioó las llaves y se las poneuso sobre la mesa del garaje.

I think that this is supposed to be in past tense. "Limpió" has a written accent and is the past tense form of "limpiar." Something similar happens with "puso" and "poner."

- Pedro no ha se compróado estos libros todavía.

Here I used the present perfect form of Spanish, which is analogous to that from English: verb have (haber) + participle (participio).

- Mientras mi hermano comería el pastel de zanahoria, mis padres leerían los libros maravillosos.

Pospretérito ---> comería, leerían (hypothetical situations, not real)
Copretérito ---> comía, leía (actions that took place in the past, real)

- Los estudiantes primero estudian porara el examen y luego van a el restaurante para comianer.

Be careful with "para" and "por." Both words have similar meanings but most of the time just one of them is actually correct. On the other hand, here you must use the infinitive form of the verb, namely, "comer" instead of "comían." And last, "a comer" in this case sounds more natural than "para comer."

- No me gusta estáa medicina porque es muy amarga.

Está ---> "Estar" (presente, indicativo, tercera persona, singular)
Esta ---> Adjetivo demostrativo (femenino, singular)

- Ella siempre olvida de cambiar su vendaje.

"Ella siempre se olvida de cambiar su vendaje" is also correct.

- El médico necesita aprender muchoas cosas.

"Cosas" is a feminine noun, so "muchas" is the right adjective.