1. Neil Armstrong became the first man __________ onto the moon.
2. On the fourth mission ___________ on the moon, astronauts took a lunar vehicle so that they could explore places further away.
答案是1.to step 2. to land
我的疑问是两个答案可以互换吗?不能的话理由是什么?是不是我猜测的land不能搭配onto?