Let's Go Further 12th13th15th5th6th7th8th9th10th11thfourteenthsixteenthseventeentheighteenthnineteenthtwenth-firsttwenty-secondtwenty-fourthtwenty-fifthtwenty-sixthtwenty-seventhtwenty-eighthtwenty-ninththirtieththirty-firstthirty-secondthirty-third1.序数词:序数词前面要加the the first (the1st) the second(the2nd) the third(the3rd)1, 20,30,40…---twenty(twentieth)…把y改成ie再加th2, 1结尾—st ..