Given:

And MainClass exists in the /apps/com/company/application directory. Assume the CLASSPATH
environment variable is set to "." (current directory). Which two java commands entered at the command line will run MainClass?（）

单项选择题Given two files, GrizzlyBear.java and Salmon.java: If both classes are in the correct directories for their packages, and the Mammal class correctly defines the findSalmon() method, which change allows this code to compile?（）

A.add import animals.mammals.*; at line 2 in Salmon.java
B.add import animals.fish.*; at line 2 in GrizzlyBear.java
C.add import animals.fish.Salmon.*; at line 2 in GrizzlyBear.java
D.add import animals.mammals.GrizzlyBear.*; at line 2 in Salmon.java

多项选择题Given: Which three are valid?（）

A.p0 = p1;
B.p1 = p2;
C.p2 = p4;
D.p2 = (ClassC)p1;
E.p1 = (ClassB)p3;
F.p2 = (ClassC)p4;

单项选择题Given: What is the result?（）

A.Compilation fails.
B.Cannot add Toppings
C.The code runs with no output.
D.A NullPointerException is thrown in Line 4.

单项选择题Given: What is the result?（）

A.Hello
B.Hello World
C.Compilation fails.
D.Hello World 5
E.The code runs with no output.
F.An exception is thrown at runtime.

单项选择题Given: What is the result?（）

A.The code runs with no output.
B.An exception is thrown at runtime.
C.Compilation fails because of an error in line 20.
D.Compilation fails because of an error in line 21.
E.Compilation fails because of an error in line 23.
F.Compilation fails because of an error in line 25.