Unit 4 Astronomy- the science of the stars课时作业

Learning about language

Ⅰ.单句写作

　　1．It_is_reported_that(据报道) a big earthquake hit the area yesterday.

　　2．How_long_did_it_take_you(花费你多长时间) to get here by air?

　　3．They_made_it_clear(他们表明) to the public that they are doing an important and necessary job.

　　4．I don't think it appropriate to_put_too_much_stress_on(给......施加太多的压力) your children.

　　5．It_is_five_years(已经5年了) since I decided on learning English.

　　6．I don't think it possible to_master_a_foreign_language(掌握一门外语) without much memory work.

　　7．John said it_was_important_to_go_on_with_the_experiment(继续这个实验是很重要的)．

　　8．Don't you agree that it_is_no_use_arguing_with_Jim(与吉姆争论是没有用的)?

　　9．He disliked_it_when_she_behaved_badly(讨厌她举止不当) in front of his mother.

　　10．It_is_a_waste_of_time_persuading(浪费时间劝说......)such a person to join us.

Ⅱ.阅读理解

　　 Here's one more reason to kick your smoking habit: A new study has found that cigarette smoking leads to disease­causing DNA damage that can last more than 30 years after a person quits.

　　 The study involved blood samples from more than 16,000 people, including present and former smokers and people who had never smoked. The researchers found evidence of a "long­term sign" in tobacco users' DNA that likely contributes to diseases associated with smoking such as lung cancer and heart disease, according to the report. Cigarettes' other hazardous effects include an increased risk for diseases like cancers, as well as lung and cardiovascular disorders.

The study's key focus was cigarettes' effect on DNA methylation(甲基化),