Alas, I have an addition to the list of unforgivable language blunders that I have committed.
I was doing my usual shift as a Spanish interpreter at the Rotacare Free Clinic last week when I was introduced to a new volunteer, a young woman from Germany who'd just signed on to help out with some clerical tasks. Since the volunteer lounge seemed to be full of Spanish interpreters at the time, all speaking Spanish and leaving her out of the conversation, I thought it would be polite as well as useful for me to try speaking a bit of German to her. I classify my German abilities as "functional," which I use to mean that I can get around in the language, but am far from fluent.
Given my tendency to mix up languages, as I've described before, I should have known better than to attempt German in an environment where I'm accustomed to speaking Spanish. I committed the usual word substitutions, generating jumbled sentences like, "Ich habe seit trece años kein Deutsch gesprochen...err, trece Jahren...err, dreizehn Jahren." Argh!
That kind of mistake, though, is frustrating but excusable. I'm far more embarrassed by how I translated my obvious need to practice conversational German: "Ich brauche...mein Deutsch üben." This falls into the category of unforgivable blunders because it's the kind of mistake that shows a fundamental lack of understanding of the language. Brauchen does indeed mean "to need", but in German, unlike in English, it does not function as an auxiliary verb. One can only use brauchen to express a need for something, as in "Ich brauche Wasser." To express a need to do something, the verb müssen must be used: "Ich muß mein Deutsch üben", or "I must practice my German."
I believe that for native English speakers, Spanish is the easiest of the European languages in part because this and similar constructions do translate literally. The elementary thought process I went through while misusing brauchen would have worked in Spanish; one can say "Necesito agua" as well as "Necesito practicar mi español". Similarly, the Spanish verb tener, "to have", functions both as a main verb meaning "to possess" and as an auxiliary verb expressing obligation: "Tengo agua" and "Tengo que practicar mi español." In this case, it's not necessary for an English speaker to discern the difference in meaning between the two uses of these verbs.
The moral: Man braucht nichts, aber man muß sich in Acht nehmen. I've learned my lesson.