With the exception of 嘆十聲 "The Mournful Sighs", which was composed in 1949 for a
Hong Kong movie and sung by the famed 白光 (Bai Guang) , the other two songs -
"Wandering Songstress" and "Song Of Four Seasons" - were composed in 1937 from
Suzhou folk songs (取材自蘇州民歌「大九連環」選曲及改編: 賀綠汀　詞: 田漢) and sung by 周璇 (Zhou Xuan )
who died of illness in Shanghai, China, at an even younger age (38) than Teresa
in 1957. Zhou Xuan with her golden voice and Teresa Teng accompanied by her
gifts, talents and versatility are still remembered today as great cultural
representatives of China in recent generations.

The first of the three
songs,嘆十聲, literally means "Sigh Ten Times". It is however very common in
Chinese
to use the multiples of ten to signify "completeness", as in
"sighing again and again". If one were to nickpick the number of times Miss Teng
has sighed in this song, a total of 3 times, the overall sentiment of the song
would have been lost. Thus, the song title has been translated as "The Mournful
Sighs".

"Wandering Songstress" and "Song Of Four Seasons" were theme
songs for the 1937 movie 馬路天使 (Street Angel). They describe the fates of the
suffering people. The metaphor of the building of the Great Wall implies the
corrupt officialdom, without regard to the welfare of the have-nots.
http://youtu.be/u6F7iYowMm0