請依下文回答第 16 題至第 20 題：
     For adventurous travelers, diarrhea is merely an embarrassing nuisance. But among poor people it is akiller. As many as half a million children are thought to die every year from enteric diseases, including choleraand dysentery. Repeated infections also   16     them, laying them open to attacks from other killers such aspneumonia. Diarrhea can even change the average   17    of a certain population. One reason Indian childrenare shorter than sub-Saharan African children from families of similar means is that they fall sick more often.
     Bangladesh, one of Asia’s poorest countries, is making huge progress   18    this misfortune. In onepart of the country with particularly good data, deaths from diarrhea and other enteric diseases have fallen by 90% in the past two decades. Along with a far-reaching   19     program and steady economic growth, thathas helped drive down the number of childhood deaths. In 1990 the under-five death rate in Bangladesh was 54% higher than the world average. Now it is 16% lower. In a country with more than 160 million inhabitants,this represents a vast   20     in human misery. Bangladesh’s success holds lessons for other poor countriesthat are trying to beat back disease.
【題組】16
(A) weaken
(B) waken
(C) fasten
(D) frighten