It does sound like "D" to me

来源: 于 2010-11-15 19:19:29 [博客] [旧帖] [给我悄悄话] 本文已被阅读：次

and we don't say STV (virus) because mainly some bacteria and parasites are pathogenic as for as "Sexual Transmission Disease"

It's a very good study pattern, I 'll follow you after I finish this semester!