To express ongoing action, German uses simple present-tense constructions such as "Ich lerne Deutsch" (I am learning German), which can describe a current activity just as in English. To talk about events that have already happened, however, German commonly uses the Perfekt tense (present perfect), which combines an auxiliary verb with a past participle. Regular verbs form the participle by adding the prefix "ge-" to the stem and the suffix "-t," so "machen" becomes "gemacht." A complete sentence reads "Ich habe gemacht," meaning "I did" or "I have made." Movement verbs, however, use "sein" instead of "haben" as the auxiliary: "gehen" becomes "gegangen," so the sentence is "Ich bin gegangen" (I went or I have gone).
Choosing between informal and formal address is one of the most important social decisions in German. The pronoun "du" is used for friends, family, children, and anyone with whom you would be on casual terms. "Ihr" is the informal plural form of "du," used when addressing multiple friends or family members. "Sie," always capitalized regardless of its position in the sentence, is the formal pronoun used for strangers, older people, colleagues, and anyone you would address with surnames. The same "Sie" form serves as both formal singular and formal plural, and the corresponding verb form is identical to the third-person plural.
Some idiomatic structures and words deserve special attention. To say "I like it" in German, you actually say "Es gefällt mir," literally "it pleases me," with the indirect object using the Dativ case. The days of the week are Montag (Monday), Dienstag (Tuesday), Mittwoch (Wednesday), Donnerstag (Thursday), Freitag (Friday), Samstag (Saturday), and Sonntag (Sunday). The basic time adverbs "heute" (today), "morgen" (tomorrow), and "gestern" (yesterday) appear constantly. Finally, beware false friends that resemble English words but mean something different: "aktuell" means current or up-to-date, not actual; "bekommen" means to receive, not to become; "Gift" means poison, not gift; "Chef" means boss, not chef or cook; "Rat" means advice, not rat; "sensibel" means sensitive, not sensible; "Handy" means mobile phone, not handy; and "Gymnasium" means a type of academic secondary school, not a gymnasium.