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.
Explanation:)
In this paragraph, Tan tells us about her personal experience with achievement tests. She describes how her mother reacted to these, and how she struggled with them, not due to her ability but due to the nature of the tests. In this way, Tan builds the central idea of her story, which is that these tests are not always accurate measures of language ability.