🪄 4A 词汇表
📖 课文原文 · LIFE BEYOND EARTH?
Is there intelligent life on other planets besides Earth? For years, scientists weren’t sure. Today, this is changing. Seth Shostak and Alexandra Barnett are astronomers. They believe intelligent life exists elsewhere in the universe. They also think we will soon contact these beings.
Why do these astronomers think intelligent life exists on other planets? The first reason is time. Scientists believe the universe is about 12 billion years old. According to Shostak and Barnett, this is too long a period for only one planet in the whole universe to develop intelligent life. The second reason is size—the universe is huge. Tools such as the Hubble Telescope have shown that “there are at least 100 billion … galaxies,” says Shostak. And our galaxy—the Milky Way—has at least 100 billion stars. Some planets that circle these stars might be similar to Earth.
Until recently, it was difficult to search for signs of intelligent life in the universe. Today, however, astronomers use powerful radio telescopes to listen for signals from deep space. Projects like SETI (Search for Extraterrestrial Intelligence) scan millions of radio frequencies every second. If an alien civilization sends out a radio message, our telescopes might be able to pick it up.
按课本完整原题作答，点击图片可查看大图。字母选项对应原题；填空输入原词。开放讨论与圈画题写在笔记中，不计入客观题得分。
Before You Read
Reading Comprehension
Reading Comprehension A
Reading Comprehension B
Reading Skill & Critical Thinking
Reading Skill & Critical Thinking B
🎯 1. 目标词汇发音跟读与掌握度自测
按课本完整原题作答，点击图片可查看大图。字母选项对应原题；填空输入原词。开放讨论与圈画题写在笔记中，不计入客观题得分。
Vocabulary Practice
Vocabulary Practice A
Vocabulary Practice B
Vocabulary Practice C
🏆 Unit 4A 课后荣誉通关证书
