IN THE 1970S, JEANS BECAME CHEAPER SO MANY PEOPLE ... WEARING THEM....

3. - DE KIEM TRA 1 TIET BAI SO 1
DE KIEM TRA 1 TIET BAI SO 1

3. In the 1970s, Jeans became cheaper so many people ... wearing them.

A. begin B. began C. begining D. to begin