GRE Text Completion: ETS Fundamental-GRE填空ETS基础 - UKG6_4Y0Z76OTFFPX

Natural selection tends to eliminate genes that cause inherited diseases, acting most strongly against the most severe diseases; consequently, hereditary diseases that are (i)____________ would be expected to be very (ii)____________, but, surprisingly, they are not. A. lethal B. perplexing C. untreated D. refractory E. widespread F. rare