Choose the word ( A , B , C or D ) that best fits the blank space in the following passage :
   There are many places to visit in Vietnam . Ha Long Bay is in Quang Ninh Province . It is a UNESCO World Heritage (19)....It's in the north (20)...Vietnam . Visitors can go to Ha Noi (21)...plane and then take a bus to Ha Long Bay. They can visit small islands and (22)...amzing caves there . Another well-known place is Tra Su Forest in An Giang Province . Tourists can take a bus from Ho Chi Minh City to get there . The (23)...time to visit this forest is from September to November , (24)...visitors can see thousands of birds , forests animals and fish there .
19.A.site B.place C.tourism D.home
20.A.by  B.on       C.in         D.of
21.A.with B.by  C.on  D.in
22.A.get  B.locate C.hike  D.explore
23.A.good B.best C.better D.most
24.A.when B.where C.that D.but