下面的哪些程序段可能导致错误? ( ) Ⅰ:String s="Gone with the wind"; String t="good"; String k=s+t; Ⅱ:String s="Gone with the wind"; String t; t=s[3]+"one"; Ⅲ:String s="Gone with the wind"; String standard=s.toUpperCase(); Ⅳ:String s="home directory"; String t=s-"directory";
- AⅡ、Ⅲ
- BⅡ、Ⅳ
- CⅠ、Ⅳ
- DⅢ、Ⅳ