yes针对的是啥，得看上下文。假如上文问是否con,oppose之类，回答yes就是同意反对。只能说给出的语境不完整。

Asked if she opposed immunization, she wanted to know if vaccines come from animal research. When assured they do, she replied, "Then I would have to say yes."被问及她是否反对免疫接种时，她反问疫苗是否来自动物研究。得到对方确认回答后，她答曰：“我反对。”正确理解的关键点在于：“yes"的完整回答是：Yes, I do (oppose immunization.")

语句的理解，不可以脱离文章上下文，不可以断章取义

不会是忘了have to的意思了吧