Este aparato era sumamente útil en el siglo XIX. - ¿Qué hacía? ¿Para qué servía?This device was extremely useful in the 19th century. - What did it do? What was it for?
Esta es mi oficina y esas son mis cosas. ¿Qué hacía? ¿Por qué está husmeando?This is my office, and these are my things. What were you doing? Why are you snooping around?