在宏定义#define PI 3.14159中，用宏名PI代替一个______。
参考答案：字符串
解析： 本题考查字符替换格式：#define标识符字符串。
下列历史事件改变了社会性质且性质相同的有
①中国戊戌变法②俄国1861年改革③日本明治维新④美国罗斯福新政[ ]
A．②③
B．①②
C．②④
D．①④
句型转换 。
1. They are cleaning the house.(对划线部分提问)
are they ?
2. My brother is playing football.(改为否定句)
My brother playing football.
3. Peter is eating dinner now.(改为一般疑问句)
Peter dinner now?
4. He wants to go to the movies.(改为否定句)
He to go to the movies.
5. Are they watching TV? (作肯定和否定回答)
Yes, .／No, .
