Learning mandarin Chinese (a.k.a. "pu tong hua") is a real challenge compared to most European languages. In some ways it is easy, as words do not change with gender, number or even tense, and there are few grammatical traps. However you got to pronounce the five tones correctly (flat, down-up, up-down-up, up-down, neutral) and peculiar sounds such as "c", "x", "ch", "sh", "zh" ... (as transcribed in pinyin) or you might say very rude or totally absurd things without being aware.