21.  Another example dated back to the Second World War.

22.  These traditional gender roles were the norm back then and, to a certain extent, are still observed today.

23.  Luckily all her did has paid back one day.

24.  It's crucial for me to reflect back on my past gains and losses in English learning and make a plan to sharpen my English ability.

25.  Before coming to the conclusion, we had better look back on the origin of the issue which dates back from the early history of human beings.

26.  Trace back to the past in my English learning, I have kept a lot of words in my mind and I am proficient in reading.

27.  Before looking to the bright future , turning back your head to reflect on the past is necessary.

28.  This traditional family can date back to the Stone Age.

29.  It is still like a dream that after working in a company for one year , I become a postgraduate and come back to NanJing University again .

30.  The day of looking back on my learning English, gains and losses coexist.