下面这段话中的take him up on the offer 怎么翻译才好呢？

Question

In January, President Hu visited Walter Payton College Preparatory High School in Chicago during his state visit to the US. He praised the school's Chinese-language courses and invited 20 students to visit Beijing this summer.

The students took him up on the offer on Friday, by visiting Zhongnanhai. President Hu extended a warm welcome and chatted with each of the students. The students presented the Chinese president with a photo album including pictures of Hu's visit to their school.

Answer 1

一月时，在其赴美国事访问时，胡总书记曾造访过Walter Payton学院预备高中。他对该校汉语课程给予高度评价，并邀请20位学生这个暑假回访北京。
周五，应总书记之邀，这群学生访问了中南海。胡总书记表示热烈欢迎，和每位学生进行交流。这群学生将包括当初他访问其校之照在内的影集（或：相册）赠送给中国国家主席。

take him up on the offer：应他（=胡总书记）之邀、应他邀请。

Answer 2

我只找到一些例句，具体我也不清楚，希望有帮助
He promised us "Every Day Low Prices , " and took him up on the offer .
他应允“天天低价”的时候，他就代为提供。
They took him up on the offer, and within weeks not only had he gained professional experience the drugstore decided to pay him for his efforts .
他们就按他的条件接受了他。经过几周的工作之后，他获得了专业经验，杂货店也决定为他的劳动付酬。
If GM doesn't take Waldron up on the offer , Pontiac will be shut down by 2010 .
通用汽车没有考虑沃尔德伦提供上，庞蒂亚克将被关闭，到2010年

Answer 3

took him up on the offer 接受他的提议（邀请）

Answer 4

take sb. up on sth.意思是接受sb的sth（有接受并开始sth的意思）。我觉得字字不好翻，不过这整句联系上下文可以翻成：学生们周五从中南海开始了他们的北京之行