1.      ¹The human heart is the size of a clenched fist. ²It is enclosed in a sac just under the breastbone. ³The heart is formed mostly of cardiac muscle tissue. ⁴Its thin-walled atria collect blood returning to the heart. ⁵Then the blood is pumped a short distance to the ventricles. ⁶The thicker-walled ventricles pump blood to all other body organs. ⁷The heart is the hub of the circulatory system. ⁸In an ongoing, rhythmic cycle, it fills with blood from the large veins. ⁹Then it contracts, pushing the blood throughout the body. ¹⁰Its alternating relaxations and contractions make up the cardiac cycle. ¹¹When the entire heart is relaxed, blood flows into all four of its chambers. ¹²This phase is called diastole. ¹³The other part of the cardiac cycle is called systole. ¹⁴Systole begins with a very brief contraction of the atria that completely fills the ventricles.

Topic sentence(s):  

2.      ¹The rate of teen births in the United States has gone down steadily. ²In 1996, 500,000 babies were born to mothers who were 15 to 19 years of age. ³About 75 percent of these young women were not married. ⁴An additional 11,000 babies were born to mothers who were 14 or younger. ⁵All of these mothers were unmarried. ⁶Despite the decline in the teen birthrate, the number of teen births to unmarried young women continues to grow. ⁷One reason for the teen birthrate is poverty. ⁸A second reason is low academic success. ⁹A third, and major, reason is sexual coercion. ¹⁰As many as 50 to 70 percent of babies born to girls aged 11 to 18 are fathered by men who are four to seven years older than the mothers. ¹¹The reasons and numbers of teen births are still alarming.

Topic sentence(s):  

3. ¹Even before a person begins to walk and talk, she becomes aware of the rules that govern her behavior. ²Mother says, "No!" whenever she touches the television. ³She learns that food should not be thrown on the floor or eaten with fingers. ⁴As the person internalizes these rules and values, a Parent ego state develops. ⁵The Parent ego applies self-control to a person's behavior. ⁶There are two forms of parent behavior. ⁷One is the Nurturing Parent, and the other is the Critical Parent. ⁸The Nurturing Parent is supportive and helpful. ⁹Children copy this behavior in their play as they pretend to be doctors, nurses, and other caregivers. ¹⁰The Critical Parent sets up rules about what is "good" and "bad."

Topic sentence(s):  

B. Identify the central idea of the following passage.

4.      ¹Matt Drudge and his brand of cyberreporting have changed the whole news cycle in America. ²Drudge was 30 years old when he broke his first story about Monica Lewinsky's relationship with President Clinton. ³This relationship became the biggest political scandal of the 1990s. ⁴Drudge had never been trained in journalism or hired by any media outlet. ⁵He had not verified the story, nor did he do any research. ⁶All he had to go on was a rumor that Newsweek had been working on the story. ⁷Newsweek had decided not to print the story in that week's issue. ⁸But for Drudge, a rumor was good enough to report on. ⁹No editor was going to tell him that he needed confirmation, because Drudge worked on his own. ¹⁰He didn't have to worry about the damage to his publication because he didn't have one. ¹¹He got his "Drudge Report" out through an e-mail list and by posting it on his Web site (www.drudgereport.com). ¹²When Drudge hit the Enter button on his computer to post the story, he knew his life would be changed forever, and for some time so would the nation's. ¹³Matt Drudge and his brand of cyberreporting have changed the whole news cycle in America.

Central idea: