is it grammatically correct to say is it grammatically correct to say "In the course of human history, we've always wanted to explore the universe" ?

Does it make sense to say This question is for American English speakers. Does it make sense to say " I am not solid on that subject" as in I am not very familiar with the subject? For example, I am not solid on Math

Mir fehlt ein Buch vs Ein Buch fehlt mir Mir fehlt ein Buch vs Ein Buch fehlt mir Does word order matter in this sentence? I understand that the verb is in the second position. What about dative(mir) and the subject(ein buch)? Are these two sentences interchangeable? Which one is more commonly used? Vielen Dank.

What does "πότε έχετε το αεροπλάνο" mean? I was listening to an audio file and someone mentioned "πότε έχετε το αεροπλάνο". My understanding is that it means "When is your airplane(when does the plane take off)?" Why is the word έχετε used here? and how do you answer the question?

American English aw and ah TIL in some areas of the US, people don't use the ɔ sound(aw as in the British way of saying hot ). Is this true? There is obviously a difference between the two sounds. Take the word "Law" for example, L(aw) and L(ah, ah as in father) don't sound the same? What's the most "legit" way to pronounce it (eg. General American accent)? Can someone clarify this for me?

Warum fängt das Oktoberfest schon im September an? Hallo zusammen ich habe eine Frage. Warum findet das OKTOBERfest im September statt und warum heißt das Oktoberfest nicht SEPTEMBERfest? Oder anders gefragt : Warum findet es nicht im Oktober statt, wenn es doch so heißt? Vielen Dank.

What is the difference between these two sentences? Have you finished it? Did you finish it? I understand that one is simple past tense and the other is present perfect tense. what's the difference in meaning between the two?And also, Are you finished?

(Go) out on a limb? "I'm going to go out on a limb here and declare that Facebook is the most intense website in the world." What does "go out on a limb" mean? Could someone paraphrase it for me?

Je ne sais pas (._. ) Hier, je suis allé au cinéma. Aujourd'hui, je ne travaille pas. Ce matin, je viens de manger un sandwich. Je suis en train de prendre un examen de français. Le examen est très difficile pour moi :'(. Je suis sur le point de pleurer. Demain, je vais nager avec mes amis. La semaine prochaine, je vais acheter un livre pour mon ami.