Trade and c    1     have often f    2     the foundation of mankind’s greatest a    3    . To c    4     the great map of the world was a strong p    5     for the people of early civilisations. Marco Polo’s t    6     inspired European explorers to s    7     for sea r    8     from west to east. H    9    , merchants and explorers from the East set s    10     from east to west many years before Columbus first did.

A decade after America     1     (退出) from Vietnam, the seeds of the often heart-breaking history, A Piece of My Heart, were sown when writer and filmmaker Keith Walker met a woman who had been an emergency room nurse in Cu Chi and Da Nang. She and 25 others       2     (回想) the time they spent in Vietnam as part of the 15,000 American women who volunteered or served as nurses in the military. After working on too many mutilated (截肢的) young     3     (士兵), one nurse talked of wanting to ask her mother to “check around and see if she could find one whole eighteen-year-old”.

Many returned with post-traumatic stress disorder (创伤后精神紧张性障碍). They still felt     4     (惊恐) rising within them. “The one thing Vietnam did for me was that I felt like I could walk on water,” said a nurse.