JohnSnowwasafamousdoctorinLondon—soexpert,indeed,thathe...
问题详情：JohnSnowwasafamousdoctorinLondon—soexpert,indeed,thatheattendedQueenVictoriaasherpersonal 61 (physics).Buthebecameinspiredwhenhethoughtabout 62 (help)ordinarypeopleexposedtocholer...