xiaomei, most of the time any kind of rape situation happens - whether it's attack rape on the town, abusive rape/forced sex by the partner at home, date rape or a teacher or priest making advances on a child - it's not something that just strikes from one second, even one minute, to the next. Most people who have described such situations make it clear that there was a lead-up for some time, a stretch where the assailant got increasingly pushy, close and perhaps ultimately aggressive. Oral research studies about rape provide the same picture. Unless the rapist has chosen to lace a drink with some dizzying drugs or resorts to jumping on the victim like a wolf, the classical "rape rape" situation, there IS nearly always a lead-up time that can provide a good deal of options for the victim to adjust her behaviour in order to discourage the rapist, to call attention from others or just get up and get out.
Sometimes the victim won't feel up to using those opportunties, or she may not have learnt to read them or maybe she is too cowed already, too immersed in the feeling that she really deserves to be punished or that anyway she's safe with this guy, if it's her partner: she knows him. I don't think most people would say one is to *blame* morally for one's getting raped if there are no changes to behaviour during the run-up time, but it does matter what you do during that time, whether you stay, what you say, what kind of movements you make and so on