出行方式一般都有两种表达方式，一种是动词＋to ＋the place. 一种是go to some place by＋交通工具。步行有两种表达方式：

1.walk to some place.

2.go to some place on foot.

所以海伦总是步行去动物园可以表达为

1.Helen always walks to the zoo.

2.Helen always goes to the zoo on foot.