.— I ‘ll ask our physics teacher to explain Newton’s Second Law of Motion, which she taught us yesterday.— That’s just _______ most of the students haven’t understood.
Tom: My brother will be surprised when he opens this package I’m sending. Jack: Why are you sending him a package? Tom: __________.
Both the man and his horse ________ after the long ride.
When you ______ the book please return it to the library on time.
——You look so worn-out!——I lay ________ all the night.
Joe: Why don't you tell me a few things about your country? Ken: __________