Science is _____ difficult for some students ____ learn, so many of them don’t like it.
________ it is to visit theme parks in Beijing!
John ________ South Hill. He will be back ________ a few days.
Jim has many hobbies, ________ swimming, hiking and playing badminton.
Mary _______ to see the films because she ________ it twice.
--- Lucy hasn’t come back from the library ________.--- Yes, I have ________ called her.