. It used to be thought _____ the Earth was flat.
Great changes _____ in China in the past 30 years and many Chinese are living a happy life today.
Unfortunately, the couple _______ after years of quarrels .
This book _____ ten units, ______ three mainly revision.
The book is _______ that one.
Last winter, many places of southern China were struck by heavy snowstorms, __________more than 120 people were killed.