** the arguer assumes that just because one event follows another， the second event has been caused by the first. / however， no evidence is provided to support that this is the case. / the mere fact that a occurs before b does not necessarily establish a causal relationship between a and b. / it is highly possible that other factors might also bring about these same results. / for instance，… in addition，… / without ruling out these and other possible factors that give rise to b， the author cannot confidently conclude that…
** the recommendation depends on the assumption that no alternative means of doing sth are available. / however， the arguer fails to offer any evidence to substantiate this crucial assumption. it is highly possible that means other than this would better solve the problem. / without considering and ruling out these and other alternative means of doing sth， the author cannot confidently conclude that…
** the arguer assumes the characteristics of a group apply to every member of that group. / the conclusion that… is based on the assumption that … / however， there is no guarantee that this is the case， nor does the author provide any evidence to substantiate this assumption. it is very likely that… / lacking such evidence the author cannot draw any firm conclusion. (整体规律不一定适用于个人)
** it is assumed without justification that background conditions have remained the same at different times / conditions. / the arguer unfairly infer from… in the past that… / however， he/she fails to offer any evidence to substantiate this inference. it is very likely that…， or that… / any of these scenarios， if true， would serve to undermine the claim that… (从过去不能推知现在和将来)
finally， the arguer provides no assurances that the survey on which the argument depends is statistically reliable. / lacking information about the number of … surveyed and the number of respondents， it is impossible to assess the validity of the results. /for example， if… were surveyed but only… responded， the conclusion that… would be highly suspected. / another problem is the representativeness of the respondents. were they representative of all the…? were… chosen for the survey chosen randomly or did they volunteer for the survey?… / lacking such evidence the author cannot draw any firm conclusion based on the study.