程序代写代做代考 python Starting Out with Python 4e (Gaddis)

Starting Out with Python 4e (Gaddis)
Chapter 3 Decision Structures and Boolean Logic

TRUE/FALSE

1. The Python language is not sensitive to block structuring of code.

ANS: F

2. The if statement causes one or more statements to execute only when a Boolean expression is true.

ANS: T

3. Python allows you to compare strings, but it is not case sensitive.

ANS: F

4. Nested decision statements are one way to test more than one condition.

ANS: T

5. Python uses the same symbols for the assignment operator as for the equality operator.

ANS: F

6. The not operator is a unary operator which must be used in a compound expression.

ANS: F

7. Short -circuit evaluation is only performed with the not operator.

ANS: F

8. Expressions that are tested by the if statement are called Boolean expressions.

ANS: T

9. Decision structures are also known as selection structures.

ANS: T

10. An action in a single alternative decision structure is performed only when the condition is true.

ANS: T

11. The following statement will check to see if the turtle’s pen color is ‘green’:
if turtle.pencolor() = ‘green’

ANS: F

12. The following code snippet will change the turtle’s pen size to 4 if it is presently less than 4:
if turtle.pensize() < 4: turtle.pensize(4) ANS: T MULTIPLE CHOICE 1. A(n) __________ structure is a logical design that controls the order in which a set of statements execute. a. function b. control c. sequence d. iteration ANS: B 2. The decision structure that has two possible paths of execution is known as a. single alternative b. double alternative c. dual alternative d. two alternative ANS: C 3. Multiple Boolean expressions can be combined by using a logical operator to create __________ expressions. a. sequential b. logical c. compound d. mathematical ANS: C 4. When using the __________ logical operator, one or both of the subexpressions must be true for the compound expression to be true. a. or b. and c. not d. maybe ANS: A 5. Which logical operators perform short-circuit evaluation? a. or, not b. not, and c. or, and d. and, or, not ANS: C 6. Which of the following is the correct if clause to determine whether y is in the range 10 through 50, inclusive? a. if 10 < y or y > 50:

b.
if 10 > y and y < 50: c. if y >= 10 and y <= 50: d. if y >= 10 or y <= 50: ANS: C 7. A Boolean variable can reference one of two values which are a. yes or no b. True or False c. T or F d. Y or N ANS: B 8. What is the result of the following Boolean expression, given that x = 5, y = 3, and z = 8? x < y or z > x
a.
True

b.
False

c.
8

d.
5

ANS: A

9. What is the result of the following Boolean expression, given that x = 5, y = 3, and z = 8?
x < y and z > x
a.
True

b.
False

c.
8

d.
5

ANS: B

10. What is the result of the following Boolean expression, given that x = 5, y = 3, and z= 8?
not (x < y or z > x) and y < z a. True b. False c. 8 d. 5 ANS: B 11. What does the following expression mean? x <= y a. x is less than y b. x is less than or equal to y c. x is greater than y d. x is greater than or equal to y ANS: B 12. Which of the following is the correct if clause to determine whether choice is anything other than 10? a. if choice != 10: b. if choice != 10 c. if choice <> 10:

d.
if not(choice < 10 and choice > 10):

ANS: A

13. When using the __________ logical operator, both subexpressions must be true for the compound expression to be true.
a.
or

b.
and

c.
not

d.
either or or and

ANS: B

14. In Python the __________ symbol is used as the not-equal-to operator.
a.
==

b.
<>

c.
<= d. != ANS: D 15. In Python the __________ symbol is used as the equality operator. a. == b. <>

c.
<= d. != ANS: A 16. Which of the following will hide the turtle if it is visible? a. if turtle.isvisible(): turtle.invisible() b. if turtle.isvisible turtle.hideturtle() c. turtle.isvisible(): turtle.hide() d. if turtle.isvisible(): turtle.hideturtle() ANS: D 17. Which of the following will determine if the turtle's pen is up and will change it to down if that is the case? a. if turtle.isup(): turtle.isdown() b. if turtle.isdown turtle.penup() c. if not(turtle.isdown()): turtle.pendown() d. if not(turtle.penup()) turtle.penup() ANS: C COMPLETION 1. The ___________ statement is used to create a decision structure. ANS: if 2. In flowcharting, the __________ symbol is used to represent a Boolean expression. ANS: diamond 3. A(n) __________ decision structure provides only one alternative path of execution. ANS: single alternative 4. In a decision structure, the action is ___________ executed because it is performed only when a specific condition is true. ANS: conditionally 5. A(n) __________ operator determines whether a specific relationship exists between two values. ANS: relational 6. A(n) __________ statement will execute one block of statements if its condition is true or another block if its condition is false. ANS: if-else 7. Python provides a special version of a decision structure known as the __________ statement, which makes the logic of the nested decision structure simpler to write. ANS: if-elif-else 8. The logical __________ operator reverses the truth of a Boolean expression. ANS: not 9. Boolean variables are commonly used as __________ to indicate whether a specific condition exists. ANS: flags 10. A(n) ___________ expression is made up of two or more Boolean expressions. ANS: compound 11. The turtle.isdown() function returns ___________ if the turtle's pen is down. ANS: True