SO THAT

En la oración final introducida por so that, normalmente[1], aparecerá un verbo modal del tipo can, may, will..., excepto si es negativa.

                    I'm going to stay in London for a year so that I can improve my English.

            I'm going to stay in London for a year so that I may improve my English.

            I turned down the TV volume so that my sister could study  

            We gave him a brochure so that he may have all the information.

           

            I'll take a jacket so that I don't get cold

            I’ll take a jacket not to get cold

            I brought a jacket so that she didn’t get cold

En un etilo más informal se puede prescindir de that.

            I've come early so I can talk to you

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[1] Esta estructura se utiliza obligatoriamente cuando el sujeto de la oración principal es distinto del de la subordinada final.