题目内容

解释：复合光和单色光，红移和紫移，增色效应和减色效应

查看答案

搜索结果不匹配？点我反馈

更多问题

举例说明生色团和助色团。

为什么原子光谱呈线状光谱，而分子光谱呈带状光谱？

Directions: Now, you will hear three news reports. At the end of each news report, youwill hear two or three questions. Both the news report and the questions will be spoken only once. After you hear a question, you are supposed to choose the best answer from the four choices marked A), B),C) and D).Questions 1 and 2 will be based on News ltem 1.[音频]

A. From a used car.
B. From Halfords.
C. From manufacturers.
D. From DIY store.

2

A. One weekend.
B. One week.
C. Ten days.
D. Half a month.