s=’Python is beautiful! ’ 可以输出“PYTHON”的是 A: print(s[0:7]) B: print(s[0:7].upper()) C: print(s[-21:-14].upper) D: print(s[:-14])

s=’Python is beautiful! ’， 可以输出“python”的是： A: print(s[0:7]) B: print(s[0:7].lower()) C: print(s[-21:-14].lower) D: print(s[:-14])

下列程序段中，循环体s = s +1执行了几次？ For i = 0 To 7 Step 3 For j = 0 To 7 Step 2 s = s + 1 Next Next

下列程序段中，循环体s = s +1执行了几次？For i = 0 To 7 Step 3 For j = 0 To 7 Step 2 s = s + 1 NextNext A: 5 B: 7 C: 12 D: 49

设在坐标轴的原点有一个质量为$m$的质点，在区间$[a,a+l] (a>0)$上有一个质量为$M$的均匀细杆，设$k$为万有引力常数，则质点与细杆之间的万有引力为 A: $\frac{kMm}{a^2}$ B: $\frac{kMm}{(a+\frac{l}{2})^2}$ C: $\frac{kMm}{a(a+l)}$ D: $\frac{kMm}{(a+l)^2}$

设有如下代码段 1 String s = null; 2 if ( s != null & s.length() > 0) 3 System.out.println("s != null & s.length() > 0"); 4 if ( s != null && s.length() > 0) 5 System.out.println("s != null & s.length() > 0"); 6 if ( s != null || s.length() > 0) 7 System.out.

int s= 0; for(int sum=1; sum<=1000; ____ ){if(sum%7!=0){s = sum +s;}}System.out.println(s); A: sum+1 B: sum-1 C: sum++ D: sum--

s="Python is cool"，可以输出"python"的是 A: print(s[0:7]) B: print(s[:7].lower()) C: print(s[:-8].lower()) D: print(s[-14:-8])

设有如下代码段 1 String s = null; 2 if ( s != null & s.length() > 0) 3 System.out.println("s != null & s.length() > 0"); 4 if ( s != null && s.length() > 0) 5 System.out.println("s != null & s.length() > 0"); 6 if ( s != null || s.length() > 0) 7 System.out.println("s != null & s.length() > 0"); 8 if ( s != null | s.length() > 0) 9 System.out.println("s != null | s.length() > 0"); 哪些行将抛出空指针异常?

下列程序段的输出是___ , ___。int k;float s;for (k=0, s=0; k < 7; k ++)s += k/2;printf("%d, %.2f\n", k, s);