什么是非线性失真？
参考答案：
非线性失真：当输入扬声器中为单一频率信号时，扬声器输出声信号中含有其倍频成份，这一失真现象称为非线性失真。
根据例子将下列句子补充完整。
例: — Does your pen pal live in Beijing?
— No, he doesn't. He lives in Guangzhou.
1. — _____________ your pen pal go to work by bus?
— No, he doesn't. He _____________ to work by subway.
2. — _____________ your pen pal read newspapers every evening?
— No, he doesn't. He _____________ a magazine every evening.
3. — _____________ your pen pal watch TV in the evening?
— No, he doesn't. He _____________ TV in the afternoon.
4. — _____________ your pen pal teach math?
— No, he doesn't. He _____________ Chinese.
项目后评价工作包括两个方面：一是对项目评价时点以前已经完成的部分进行总结；二是（）。
A．对项目评价时点以后的工作进行预测
B．对项目评价时点以后的工作进行评价
C．将信息反馈到项目决策机构
D．增强项目决策、执行、管理的责任心
