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TOEFL
/
Listening practice
/ Section TZ4A
Listen to an Academic Talk
Listen to part of a talk in an immunology class.
Listen
27. Why does the speaker describe the test with cells and serum?
A
To describe how antibodies were first purified
B
To show how simple the solution became once the idea existed
C
To explain why the test is no longer used
D
To argue that laboratory work was expensive