串的长度是( )。
A．串中不同字符的个数
B．串中不同字母的个数
C．串中所含字符的个数且字符个数大于零
D．串中所含字符的个数
参考答案：D
箱形电阻炉。
常用温度是（）
A.1000℃
B.950℃
C.800℃
D.1200℃
E.1100℃
— Is that a new car?
— No, I _____ it two years ago. [ ]
A. have
B. buy
C. have had
D. bought
