单选题Which will declare a method that forces a subclass to implement it？ （）APublic double methoda（）；BStatic void methoda （double d1） {}CPublic native double methoda（）；DAbstract public void methoda（）；EProtected void methoda （double d1）{}

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Action

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RenderAction

A final method in class X can be abstract if and only if X is abstract.

A protected method in class X can be overridden by any subclass of X.

A private static method can be called only within other static methods in class X.

A non-static public final method in class X can be overridden in any subclass of X.

A public static method in class X can be called by a subclass of X without explicitly referencing the class X.

A method with the same signature as a private final method in class X can be implemented in a subclass of X.

A protected method in class X can be overridden by a subclass of X only if the subclass is in the same package as X.

Local variables defined inside a method are destroyed when the method is exited.

Local variables are also called automatic variables.

Variables defined outside a method are created when the object is constructed.

A method parameter variable continues to exist for as long as the object is needed in which the method is defined.

 Public double methoda（）；

 Static void methoda （double d1） {}

 Public native double methoda（）；

 Abstract public void methoda（）；

 Protected void methoda （double d1）{}

 abstract public void methoda （）；

 public abstract double inethoda （）；

 static void methoda （double dl） {}

 public native double methoda （） {}

 protected void methoda （double dl） {}

It forces hot air out of the PC

The fan is easier to remove and clean

It forces cooler air into the power supply quickly

It forces cooler air across the motherboard

 Use the following code to declare the FindAttribute method： public T FindAttribute （T att） {//Find attribute and return the value }

 Use the following code to declare the FindAttribute method： public object FindAttribute （object att） {//Find attribute and return the value }

 Use the following code to declare the FindAttribute method： public T FindAttribute  （T att） {//Find attribute and return the value }

 Use the following code to declare the FindAttribute method： public string FindAttribute （string att） {//Find attribute and return the value }

the center of volume of the immersed portion of the vessel

the center of gravity of the water plane

that point at which all the vertical downward forces of weight are considered to be concentrated

that point at which all the vertical upward forces of buoyancy are considered to be concentrated

A class’s finalize（） method CANNOT be invoked explicitly.

super.finalize（） is called implicitly by any overriding finalize（） method.

The finalize（） method for a given object is called no more than once by the garbage collector.

The order in which finalize（） is called on two objects is based on the order in which the two objects became finalizable.

It forces the bow away from the bank

It forces the stern away from the bank

It forces the entire vessel away from the bank

It heels the vessel toward the bank

The charAt（） method of the String class.

The toUpperCase（） method of the String class.

The replace（） method of the String class.

The reverse（） method of the StringBuffer class.

The length（） method of the StringBuffer class.

 Abstract public void methoda（）；

 Public abstract double methoda（）；

 Static void methoda（double d1）{}

 Public native double methoda（）  {}

 Protected void methoda（double d1）  {}

public void DoWork（）；

public void DoWork（int nCounter）；

public void DoWork（object oCounter）；

public void DoWork（Delegate oCounter）；

soft mud

sand

silt

soft to firm clays

Instances of class Thread have a method called notify（）.

A call to the method notify（） will wake the thread that currently owns the monitor of the object.

The method notify（） is synchronized.

The method notifyAll（） is defined in class Thread.

When there is more than one thread waiting to obtain the monitor of an object， there is no way to be     sure which thread will be notified by the notify（） method.