Theproblem________whenthestudentsrefusedtodotheirhomework.
Idon'tknowhowwecanmake________onthetimetableforanymorecourses.
Sorrysir,wedon'thavewineorbeer.Weareonlylicensedtosell_______drinks.
Humanbehaviorismostlyaproductoflearning________thebehaviorofanimalsdependsmainlyoninstinct.