石材幕墙的石板厚度不应小于()，为满足等强度计算要求，火烧石板的厚度应比抛光石板厚3mm。
A. 15mm
B. 20mm
C. 25mm
D. 30mm
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What may happen if a person has got a coupon？
A. He may keep it.
B. He may give it to his relative.
C. He may buy more things.
劳动和受教育即是公民的权利也是公民的义务。()
A. 正确
B. 错误
【C17】
A. or
B. and
C. but
D. that
What is the main idea of paragraph 2？
A. The influences from parents to children's competence can be either positive or negative.
B. Parents' beliefs and behaviors are strongly related to children's psychological and behavioral outcomes.
C. Parents who give less pressuring can raise more competitive athletes.
D. With the encouragement from parents, children can have inner motivations themselves.
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