Monkeys in the zoo started to show the flu last Monday and altogether twenty have died up to now．
A. symbol
B. sign
C. signal
D. symptom
网友回答
A. symbol
B. sign
C. signal
(答案→)D. symptom
解析： 词义辨析symbol符号，sign迹象，signal 信号，symptom 症状 动物园里的猴子上周一开始出现流感症状到目前共死了20只。选D