题目

听下面一段独白，回答以下小题。【1】Who is the speaker?A. A student. B. A professor. C. A teacher’s helper.【2】What is the class mainly about?A. Electricity.B. Modern science.C. Science in ancient Greece and Rome.【3】What was calculated correctly by an ancient Greek?A. The size of the earth.B. The size of the moon.C. The distance between the moon and the earth.【4】What will the speaker do next?A. Talk about Archimedes.B. Explain a math problem.C. Answer some questions.用数字和化学符号填空（1）氯原子________　　　　　　　 （2）2个钠离子________（3）3个二氧化碳分子________　　 （4）+1价的氢元素________（5）氧化铜中铜元素的化合价为+2________．