Question

my sister often help old people with housework对不对

Answer 1

不对。应该是My sister often helps old people do（to do，with） some housework.
helps my mother do（to do，with） some housework．首先通过中英文句子的比对，可知英文句子中缺少"帮助妈妈做家务"的表达．短语"帮助妈妈做家务"的英文表达是：help my mother do（to do，with） some housework．本题中，句子表述的经常性 习惯性的动作，所以用一般现在时，故答案为：helps my mother do（to do，with） some housework