Okay, consider "to cleave", which can mean "to split apart" or "to stick together". How many languages have a word that means both? But that doesn't imply that those languages lack ways to express such basic concepts as splitting or not splitting, just because the language lacks any particular word that means both.
I think that it is perfectly plausible that you could have a language without any strict distinctions between verbs and nouns and adjectives. If you look at a lot of "primitive" English words, that distinction isn't present in the word itself. Other languages like Korean use modifiers to dictate what part of speech a word is being used as in a particular sentence, so most nouns can be turned into verbs or vice versa.
Noting that there is no precise equivalent for any given word from one language in some unrelated language is therefore not very significant. For a verb like "to be", which has many different meanings depending on how it is used (many of those meanings being purely grammatical, such as meaning that the following adjective is being used as a verb), it is so unlikely that another language would have some word with all the exact same uses that it would be far more relevent to point out another language that did have an exact equivalent.
"to become" means "to come into existence", and can probably be modified using tense to express existence. Here we run into the reverse side of the coin I mention above, refusing to translate a term from another language in context and insisting that there is a precise equivalent in English to any particular word from another language. Very often, a given word in another language could be justifiably translated as any one of several English words (or terms), depending on its usage. If we take the stance that "because this word can't always be translated as X, it should never be translated as X" then translation becomes very difficult, particularly for the core vocabularies of languages that aren't closely related.
