I study english because sometimes I have to speak it. I study english because sometimes I have to speak in english in my job. I think you should merge these two sentences together since they sound a little repetitive. Something like "I study English because sometimes I have to speak it in places like my job." By the way the first letter of languages should be capitalized. Because sometimes I have to speak in english in my job I have decided to learn english For this sentence, I would say: "I decided to learn English since I have to speak it/use it at my job." Also, in English we don't do the two question marks but I think it's cool that you do it in Spanish. :D