Passage 1
Wilma Subra had no intention of becoming a public speaker.
After graduating from college with degrees in chemistry and microbiology,she went to work at Gulf South Research Institute in Louisiana.
As part of her job,she conducted field research on toxic substances in the environment,often in minority communities located near large industrial polluters.
She found many families were being exposed to high,sometimes deadly levels of chemicals and other toxic substances.
But she was not allowed to make her information public.
Frustrated by these restrictions,Subra left her job in 1981,created her own company and has devoted the past two decades to helping people fight back against giant industrial polluters.
She works with families and community groups to conduct environmental tests and hybrid test results,and organize for change.
Because of her efforts,dozens of toxic sites across the country have been cleaned up.
And one chemical industry spokesperson calls her"a top gun"for the environmental movement.
How has Subra achieved all this?
Partly through her scientific training,partly through her commitment to environmental justice.
But just as important is her ability to communicate with people through public speaking.
"Public speaking,"she says,"is the primary vehicle I use for reaching people."
If you had asked Subra before 1981,do you see yourself as a major public speaker?
She would have laughed at the idea.
Yet today she gives more than one hundred presentations a year.
Along the way,she's lectured at Harvard,testified before congress,and addressed audiences in 40 states,as well as in Mexico,Canada,and Japan.

Questions 26 to 29 are based on the passage you have just heard.
26. What did Wilma Subra do as part of her job while working at Gulf South Research Institute?
27. Why did Wilma Subra leave her job in 1981?
28. What results have Wilma Subra's efforts had in the past two decades?
29. What does the speaker say has contributed to Wilma Subra's success？