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如图是生物兴趣小组的同学所做的“馒头在口腔中的变化”探究实验： 实验过程：1号试管：加入馒头碎屑和2mL唾液，并充分搅拌； 2号试管：加入馒头碎屑和2mL清水，并充分搅拌； 3号试管：加入馒头块和2mL唾液，不搅拌． 将三支试管都放入37℃的温水中保温10分钟，取出冷却后分别加入2滴碘液，摇匀后观察试管中馒头的颜色的变化． 实验结果及分析： （1）1号试管不变色，而2号试管和3号试管中的馒头可能变成______色． （2）1号试管中的馒头碎屑没有变色，原因是馒头中的淀粉在唾液淀粉酶的作用下变成了______． （3）2号试管中馒头碎屑变色的原因是______．3号试管中馒头块变色的原因是馒头块中的淀粉没被唾液彻底的消化，淀粉遇碘变蓝色． （4）根据实验结果解释馒头放到嘴里咀嚼时，为什么慢慢地感到有甜味______． （5）为了证明“牙齿的咀嚼，舌的搅拌”对馒头有消化作用，用______两只试管进行对照实验．
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【简答题】管导与翼导
【单选题】Windows Communication Foundation （WCF） application uses a data contract that has several data members. You need the application to throw a Serialization Exception if any of the data members are not pr...
A.
Add the Known Type attribute to the data contract.Set a default value in each of the data member declarations.
B.
Add the Known Type attribute to the data contract.Set the Order property of each data member to unique integer value.
C.
Set the Emit Default Value property of each data member to false.
D.
Set the Is Required property of each data member to true.
【单选题】The variable df is an object of type DateFormat that has been initialized in line 11. What is the result if this code is run on December 14， 2000？（）
A.
The value of s is 14-dic-2000.
B.
The value of s is Dec 14， 2000.
C.
An exception is thrown at runtime.
D.
Compilation fails because of an error in line 13.
【单选题】What exception type does the following program throw? public class Test { public static void main(String[] args) { Object o = new Object(); String d = (String)o; } }
A.
ArithmeticException
B.
No exception
C.
StringIndexOutOfBoundsException
D.
ClassCastException
【单选题】What is true about constructor?
A.
It can contain return type
B.
It can take any number of parameters
C.
It can have any non access modifiers
D.
Constructor cannot throw an exception
【单选题】What exception type does the following program throw? public class Test { public static void main(String[] args) { Object o = null; System.out.println(o.toString()); } }
A.
ArrayIndexOutOfBoundsException
B.
ClassCastException
C.
NullPointerException
D.
ArithmeticException
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