The course is still in beta, so some alternate translations are missing. Please use the "report" feature, we'll add them by and by.
i sometimes run was not accepted... we are not all born English speakers! is this a mostake in English?
English adverbs have a very free word order and can usually go just about anywhere in the sentence. All of these mean exactly the same thing: "Sometimes I run," "I sometimes run," and "I run sometimes."