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11.    English/ has/ Mr. Nam/ 20/ taught/ for/ years/.
12.    Vietnam/ has/ to/ She/ never/ been/ before/.
13.    her/ haven't/ I/ met/ the/ years/ for/ last/ 3/.
14.    have/ an/ novel/ never/ I/ read/ interesting /such/ before/.
15.    I/ been/ to/ before/ Hanoi/ have/ twice/.