缺一不可

not a single one is dispensable / can't do without either

no; not so / (bound form) not; un-

one / single / a (article) / as soon as / entire; whole; all; throughout / "one" radical in Chinese characters (Kangxi radical 1) / also pr. [yao1] for greater clarity when spelling out numbers digit by digit

can / may / able to / to approve / to permit / to suit / (particle used for emphasis) certainly / very

used in 可汗[ke4 han2]

cannot / should not / must not

cannot; should not; must not

deficiency / lack / scarce / vacant post / to run short of