If you are free to walk through out city, please ________ us.A drop in B drop in at C. drop in on
—Susan, can you help me clean the window? —Why_______? Alice is sitting there doing nothing.
—Is Christmas ______ December 25th or 26th ? —25th, I think.
—Look! Here is a book about the history of Britain! —Really? Please show me _______ book.
—Excuse me. How much is the shirt? — _______.
---_____ is Mike? ---He is in the classroom.