Answer:
Tan gives an example of her experience with achievement tests to support the idea that they are not always accurate measures of language ability.
Step-by-step explanation:
According to the excerpt from "Mother Tongue." Amy Tan directs attention to her mother's "broken" English to prove that some standardized tests do not actually assess linguistic competence. Besides, her story also demonstrates that lack of English proficiency does not mean that a person is intellectually limited.