立即

immediately; quickly; directly; instantly; forthwith; straightaway; outright; momentarily; thereupon; promptly; pronto; p.d.q. (short for pretty damn quick); immediate; instant; prompt; immediacy; in no time; at once; right away; straight away; on the spot; out of hand; without further ado; off hand; hardly than; scarcely than; no sooner than

马上

at once; right away; right off; straight away; at any minute; without delay; right off the bat; on the spot; soon; shortly; immediately; instantly; momentarily; promptly; forthwith; pronto; ASAP; whereupon; moment; immediate; instant