trade with sb. 和……做生意；和……做交换
train
n. 火车；列车。如：
We went to Xi’an by train.
我们乘火车去了西安。
（这里的train指的是一种交通方式。）
v. 训练；培训。如：
The hunter trained his dogs to catch hares.
猎人训练他的狗去抓野兔。
She is training to become a doctor.
她正在锻炼自己成为一名医生。
（这里的train是不及物动词。）
[身临其境]
2003年高考阅读理解第61题：
By saying “The Salt Lake City Public Library is sold on the idea”, the writer means the library _______.
A. uses dogs to attract children
B. accepts the idea put forward by ITA
C. has opened a children’s department