“and so on and so forth”和“and so on”有什么区别？

没有区别，用法上没什么区别，可以通用，都是“等等”的意思。只不过在美国英语中，so on更口语化，so forth 更书面化一些。

造句：

1. And so on ; and so forth;and the like.

   等等;诸如此类

2. Shock, sepsis, acidosis, hypoxia, and so forth, are treated.

   对休克，感染，酸中毒，缺氧等应加以治疗。

3. On the desk are pens, Books, papers, and so forth."

   在书桌上有笔、书、纸等等。

4. This more complex computer could design one still more complex and so on and so on and so on.
   那个更复杂的电脑又能再设计出比自己更复杂的电脑，如此反复。

5. But after we ' d done all this prompting and teaching , he always wanted to know what we were talking about and who was going where and why did we say that and who did we say had done what , and so on and so on.
   然而在我们对他进行了促进,教导之后,他总是想知道我们在聊什么,谁要去什么地方,我们为什么那样说,为什么那样做,等等等等。