Answer:
1) The verb "ser" in the preterit imperfect tense is "era." So, the sentence would be "era una noche suave de primavera."
2)The verb "observar" in the preterit imperfect tense for María and Jose is "observaban." So, the sentence would be "María y Jose observaban al cielo."
3)The verb "turbar" in the preterit imperfect tense is "turbaba." So, the sentence would be "A veces, un viento suave turbaba las cortinas blancas."
4) The verb "mirar" in the preterit imperfect tense for the stars is "miraban." So, the sentence would be "Las estrellas miraban la luna con todo su esplendor."
5)The verb "iluminar" in the preterit imperfect tense is "iluminaba." So, the sentence would be "La luna iluminaba el cielo negro por miles de puntitos."
6)The verb "escuchar" in the preterit imperfect tense for María is "escuchaba." So, the sentence would be "María escuchaba sin interés."
7)The verb "hablar" in the preterit imperfect tense for Jose is "hablaba." So, the sentence would be "Jose hablaba con animación."