sometime girls usually ----- at----n English than boys,bur b

你们老师英语水平的确有点问题,首先sometime是错的,应该是sometimes.第二,sometimes和usually不能一起用,也就是说或者有时候或者经常.最后,根据你的中文意思,这句话应该是这样的：
girls are usually better at english than boys but boys are usually better at football than girls.