1.   I/three-week/winter holiday/so/I/go/package tour

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2.     Thanks to/British Cave Research Association/Son Doong Cave/open/the public/since 2003

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3.   Ha Long Bay/recognize/UNESCO/a site of Natural World Heritage.

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4.   Phong Nha/have/vote/ one/wonderful/ caves/world// number/ reasons.

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5.   In addition/bathing/visitors/can/take part/water sports/such/dive/surf/parachute/or/visit/fishing villages.

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