In an English exam,student A,B,C and D were in the first fou

In an English exam,student A,B,C and D were in the first four places.After the exam,A said,"I won't be the forth place." B said,"I am second,"C said ,"I am in the place before A." D said,"I am two more places ahead of C." But only one of then was wrong.Can you work out their results?(翻译+答案）（好的追加分）