I owe my success to Mr. Smith, a teacher from America, ______ help I have greatly improved my oral English.

Mr. King bought his son a new bike as a gift for his birthday.

__________ is the most difficult of all thelessons.— I agree. But it’s the most interesting.

After Mandela was free (自由的) in 1990, he chose to shake hands with the people ________ wanted to kill him.

Tom showed me his new cell phone, _______ was small but it could change colors in different weather.