Please give me full answer​

What is a verb infinitive and what does is mean to conjugate a verb?

Latin question ! translate the sentence: multa aedificia romana tanta erant ut architecti ea diu aedificarent. a. many roman buildings were so great that the architects were building them for a long time. b. many roman buildings were so big that the architects used a lot of time to build them. c. many roman buildings were so great that architects d. many roman architects built such big buildings that they took a long time to build.

What does “bangtan sonyeondan” mean?