有没搞错你？好好读这两段

Kling ended up deciding that he should use English, and that second language speakers did harm to children’s language acquisition. In coming to this conclusion, he drew on research on language development by people such as Erika Hoff. Hoff compared school test scores of Spanish-speaking immigrants to the USA who spoke Spanish to their children versus those who spoke English to them. While you might expect that the kids who spoke English at home would have higher test scores, that wasn’t true. Instead, the children being raised bilingually did better.

Kling took away from that research that non-native speakers should not speak to their children in their non-native language, and that he was doing a disservice to his daughter by speaking to her in Tagalog rather than in English. He interpreted the findings as meaning that non-native speakers are poor role models for children learning two languages, because they use ungrammatical or unidiomatic phrases.