题目

Venice is one of the most beautiful cities of the world. Venice is a cultural and tourist center and is famous for its museums, architecture, cityscape and world of art. Only about 25 % of Venice’s 280, 000 people live in the historical center of the city.   36   The main method of transportation between the islands is by taking boats that travel up and down the city’s many canals. The main waterway is the Grand Canal, which winds through the heart of Venice. Hundreds of bridges connect the island.   37   The city’s most famous church, Saint Mark’s Basilica, and the DogeStudents ________ be careful when they do chemical experiments in the lab.A.can B.must C.need D.may