試題詳解

160 
Which code fragment, inserted at line 24, outputs "123abc 123abc"?
(A) sb1.append("abc"); s1.append("abc");
(B) sb1.append("abc"); s1.concat("abc");
(C) sb1.concat("abc"); s1.append("abc");
(D) sb1.concat("abc"); s1.concat("abc");
(E) sb1.append("abc"); s1 = s1.concat("abc");