填空题. "You understand grandmother when she talks to you, don't you, darling?" The girl nods. Johnson met her—and her Danish mother and English father—at the airport. The parents were eager to discuss their experience of fostering up their daughter bilingually in London. It isn't 1 easy: the husband does not speak Danish, because the child hears the 2 language only from her mother, who has come to accept that she will reply in English. This can be painful. Not sharing your first language with loved ones is hard. Not passing it on your own child can be especially tough. Many 3 immigrant parents feel a sense of failure; they share stories on parenting forums and social media, hope to find the secret to nurturing bilingual 4 children successfully. Children are linguistic sponges, but this doesn't mean that cursory exposure is enough. They must hear a language quite a bit to understand it—and used it often to be able to speak it comfortably. This is mental 5 work, and a child who doesn't have a motive to say a language—either a 6 need or a strong desire—will often avoid it. Children's brains are already busy enough. So languages often wither and die when parents move abroad. Consider America. Typically, first generation born in America is 7 bilingual, and the second is monolingual—in English, the children often struggling to speak easily with their immigrant grandparents. In the past, governments discouraged immigrant families off keeping 8 their languages. Teddy Roosevelt worried that America would become a "polyglot boarding-house" These days, officials tend to be more 9 interventionist; some even see a valuable resource in immigrants' language abilities. Yet many factors conspire to ensure that children still lose their parents' languages, or never learn it. 10