22. We know a good deal about the people who lived in China 4, 000 years ago, because they ______write and leave written records for those who lived after them.
PART TWO: LANGUAGE KNOWLEDGE Section A Directions: Beneath each of the following sentences there are 4 choices marked A, B, C and D. Choose one answer that best completes the sentence. 21. Trees are useful to man mainly in three ways, the most important of which is that they can protect ______ from droughts (干旱) and floods. A. it B. itself C. himself D. Him