Questions 9 to 11 are based on the conversation you have just heard.
A. Stimulating students to try new things.
B. Letting students learn as much as they can.
C. Teaching through interesting activities.
D. Asking students to write whatever they like.
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Questions 12 to 15 are based on the conversation you have just heard.
A. When the reason is obvious.
B. When the behavior could have negative effects.
C. When people"s behavior is illegal.
D. When the behavior is unexpected.
(2007年)层流沿程阻力系数λ( )。
A. 只与雷诺数有关
B. 只与相对粗糙度有关
C. 只与流程长度和水力半径有关
D. 既与雷诺数有关又与相对粗糙度有关
Questions 22 to 25 are based on the passage you have just heard.
A. Fourth year students are likely to get lower numbers.
B. Students have to share rooms with others in the same grade.
C. Through drawing a lot, one can only choose his roommate rather than dorm.
D. Most of the listeners can get their first or second choice.
(2005年)A、B两点之间并联了三根管道，则AB之间的水头损失hfAB等于( )。
A. hf1+hf2
B. hf2+hf3
C. hf1+hf2+hf3
D. hf1=hf2=hf3
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