a ciegas (blindly) ---*--- a cuestas (piggyback)
a diestro y siniestro (tactlessly) ---*--- a hurtadillas (secretly)
a tontas y a locas (disorderly) ---*--- a oscuras (in the dark)
a toda velocidad (at full speed) ---*--- a sabiendas (knowingly)
a la moda (fashionably) ---*--- al revés (backwards)
de buena gana (willingly) ---*--- de buen grado (willingly)
de golpe (suddenly) ---*--- de improviso (offhand)
de mala gana (reluctantly) ---*--- de mal grado (unwillingly)
de prisa (fast) ---*--- de pronto (suddenly)
de repente (suddenly) ---*--- en balde (in vain)
en resumen (in short) ---*--- en vano (in vain)
por desgracia (unfortunately) ---*--- sobre todo (above all, especially)