If you say that something is presumably the case, you mean that you think it is very likely to be the case, although you are not certain. 很可能
adverb [方式副词] 大概,可能
You'll be taking the car, presumably? 想必您是要买这辆汽车了?
You'll be taking the car, presumably? 想必您是要买这辆汽车了?