My sister often clean rooms to help my parents on Sundays .为什么clean不加s

My sister often helps Jack (study) English My sister often (study)Japanese on Sundays. My sister often helps my mum (clean)the house. My sister often helps my Mum______(clean)the house. My sister often helps me in my math.修改病句 My sister often helps me with my English的同义句是什么?句式为My sister often help me I often study English with my sister (对my sister提问 My sister often walks to school同义句My sister often____ _____ _____ _____.是四条线 My sister often helps me learn English改为同义句 My sister often gets back home ____later than we d My sister often goes shopping on Sundays.改为否定句 my little sister often _______（cry） at night My sister often goes shopping on Sundays.改为否定句 my sister often plays the piano.改为否定句 My sister often takes photos on Sundays.(改为一般疑问句) my sister often helps me怎样改成一般疑问句 my sister often（ ）（ ）（my sister often（ ）（ ）（ ）〖听磁带〗to practice listening. 最上面那个是：My sister often helps my mother co最上面那个是：My sister often helps my mother cook dinner(改为一般疑问句)