流行性乙型脑炎病毒传播媒介是
A.蚤
B.虱
C.螨
D.蚊
E.蜱
参考答案:D
一辆汽车以每小时90千米速度从甲地8:00出发,于第二天下午2时到达乙地,甲乙两地相距多少千米?
Why are naturalists inevitably pessimistic in their view