16. People in the village are suffering from some diseases resulted from the polluted water_______.
A. supply B. offering C. provide D. drinking
17. It was cold and wet. , my brother put on his swimming suit and went to the beach.
A. Therefore B. Despite C. Although D. However
18. Dams have been built in the upper reaches of the Mekong River in China and Laos to supply hydroelectricity. , it is causing big problems for people living downstream.
A. By contrast B. As a result C. However D. Besides
19. The river level drops very quickly. ______, it is difficult for boats to try to escape rocks.
A. However B. Although C. Therefore D. Otherwise
20. The coastline of Florida offers excellent white sand beaches._____, Florida has warm, sunny weather.
A. Therefore B. Moreover C. However D. Because
