单项选择题19. 执行如下代码:
import turtle
turtle.circle(100)
turtle.circle(50,180)
turtle.eirele(-50,180)
turtle.penup()
turtle.goto(0,140)
turtle.pendown()
turtle.circle(10)
turtle.penup()
turtle.goto(0,40)
turtle.pendown()
turtle.circle(10)
turtle.done()
在Python Turtle Graphics中,绘制的是
A B C D
23. 下面代码的输出结果是
s=["seashell","gold","pink","brown","purple","tomato"]
print(s[4:])
- A.['purple','tomato']
- B.['purple']
- C.['seashell','gold','pink','brown']
- D.['gold','pink','brown','purple','tomato']
A B C D
29. 以下程序的输出结果是______。
ls1=[1,2,3,4,5]
ls2=ls1
ls2.reverse()
print(ls1)
- A.5,4,3,2,1
- B.[1,2,3,4,5]
- C.[5,4,3,2,1]
- D.1,2,3,4,5
A B C D
C
[解析] 在Python中,列表对象的赋值就是简单的对象引用。本题中,ls1和ls2是一样的,他们指向同一片内存,ls2不过是ls1的别名,是引用。对l2做修改,l1也会跟着变化。ls2.reverse()是指将列表ls2中的元素反转,结果为[5,4,3,2,1],则ls1的值也为[5,4,3,2,1]。