【单选题】What will be the output of the following Python code? a=[13,56,17] a.append([87]) a.extend([45,67]) print(a) A. [13, 56, 17, [87], 45, 67] B. [13, 56, 17, 87, 45, 67] C. [13, 56, 17, 87,[ 45, 67]] D. [13, 56, 17, [87], [45, 67]]

若da={{a,b,c},{d,e,f}},那么添加一个元素{e,f}以得到列表da={{e,f},{a,b,c},{d,e,f}},可选的正确命令是:() A: PrependTo[da, e, f] B: Prepend[da,{e, f}] C: prepend[da, {e, f}] D: PrependTo[da, {e, f}]

SS3B型电力机车齿轮传动比为（）。 A: 87/20 B: 74/17 C: 88/19 D: 82/17

When was Valentine supposedly executed? A: This was on February 14, 269 A.D.. B: This was on March 14, 269 A.D.. C: This was on July 7, 269 A.D.. D: This was on January 14, 269 A.D..

若da={{a,b,c},{d,e,f}},那么添加一个元素e以得到da={{a,b,c},{d,e,f},e},可选的正确命令是:() A: Prepend[da, e] B: Append[da,{e}] C: Append[da, e] D: AppendTo[da,<br/>e]

若da={{a,b,c},{d,e,f}},那么添加一个元素e以得到{{a,b,c},{d,e,f},e},但da保持不变,可选的正确命令是:() A: append[da, e] B: AppendTo[da, e] C: Append[da, e] D: appendTo[da,<br/>e]

若da={{a,b,c},{d,e,f}},那么添加一个元素{e}以得到保持da不变的新列表{{e},{a,b,c},{d,e,f}},可选的正确命令是:() A: Prepend[da, e] B: Prepend[da,{e}] C: prepend[da, {e}] D: PrependTo[da, {e}]

设a、b、c、d都是自然数，且a5=b4，c3=d2，a-c=17，则d-b=( )． A: 269 B: 279 C: 287 D: 266 E: 255

Φ50孔，若Da=Φ50.015，f = 0.020，孔合格。

有程序：F（C，D）=A*C+B／DA=1．0B=2．0WRITE（*，*）F（A，B）+F（B，A）END此程序的运行结果是：（）