炸药探测器检查法包括（）。
A.气化物
B.痕量探测
C.电子听诊
D.核探测
参考答案：A, B
PART TWO: LANGUAGE KNOWLEDGE （45分）
Section A （15分）
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
磁化时具有微弱吸引力的物质称为（）材料
