West Nile is a tropical disease that begins in birds, which pass it on to mosquitoes that thengo on to infect human beings with a bite. Most people who  19  West Nile do not experienceany symptoms at all, but, if they do, symptoms typically develop between 3 to 14 days after amosquito bite. About 1 in 5 persons suffers fever, headaches, and body aches, and those with weakimmune systems might even die. That is  20  made the major outbreaks of West Nile in theU.S. in the summer of 2012 so scary. The situation was particularly bad in Dallas, Texas, wherethe West Nile virus killed 10 people and sickened more than 200. The city declared a  21  ofemergency and began aerial spraying of a pesticide to kill the mosquitoes, even though residentsargued that the pesticide could be more dangerous than the disease.
【題組】19.
(A) distribute
(B) contract
(C) tolerate
(D) convince