Simply put, geography is everywhere. (Page 69)

simply put相当于to put it simply，意为"简单说来"，用作插入语，一般放在句首或句中，通常做总结性状语。例如：

Simply put, your performance was far from satisfaction.

Anyway, to put it simply, we still need more money.

3. take the credit for

【课文原句】Columbus himself took the credit for this sighting. (Page 76)

take / get the credit for意为"因......而出名；因......而获得荣誉"。例如：

Peter took the credit for his invention.

【拓展】

get / take the credit本身意为"获得赞扬 / 荣誉"；give sb. credit for = give credit to sb. for意为"为......赞扬或肯定某人"。例如：

We did all the work but he gets all the credit.

The parents gave credit to their daughter for her excellent speech.

4. set foot on

【课文原句】

He never did set foot on the mainland of North America. (Page 76)

set foot on / in意为"登上；涉足；进入"。例如：

The first man to set foot on the moon is great.

I have never set foot in London.

【拓展】

set about (sth. / doing sth.) 开始做；着手做；

set off出发，动身；使（炸弹等）爆炸；

set out动身；启程；陈列；

set up建立；

set an example树立榜样

5. take upon, seek out

【课文原句】

They took it upon themselves to seek out a route to China that would avoid the Silk Road. (Page 77)

1）take it upon / on oneself to do sth.意为"自己承担起做某事的责任；亲自去做某事"。例如：

Mr. Smith took it upon himself to carry out the plan.

As a teacher, I will take it upon myself to educate every student.

2）seek out意为"挑选出；找到"。例如：

They sought out a spot where they could sit down and have a rest.

She sought out Mary to help her to complete the task.

【拓展】

seek after意为"寻找；探索；设法得到"（多用于被动语态）；seek for意为"寻找；寻求"。例如：

Early editions of Shakespeare's plays are being sought after by collectors.

They have been seeking for the lost boy for two weeks.

单元热点语法

so，not与it的替代用法