WASHINGTON--Laura Straub is a very worried woman. Her job is to find families for French teenagers who expect to live with American families in the summer.
"We have many children left to place: 40 out of 75," said Straub, who works for a Paris-based foreign-exchange program called LEC.
When exchange programs started 50 years ago, family life was more accommodating. For one thing, more mothers stayed home.
But now, increasing numbers of women work outside the home. Exchange-student program have struggled in recent years to sign up host families for the 30, 000 teenagers who annually come from abroad to spend an academic year in the US, as well as the thousands more who take part in summer programmers.
School systems in many parts of the US, unhappy about accepting non-taxpaying students, have also strictly limited the number of exchange students they accept. At the same time, the idea of hosting foreign students is becoming less exotic(异国情调的).
In searching for host families, who usually receive no pay, exchange programs are increasingly broadening their appeals to include everyone from young couples to retires.
"We are open to many different types of families," said Vickie Weiner, eastern regional director for ASSE, a 25-year-old program that sends about 30, 000 teenagers on academic-year exchange programs worldwide.
For elderly people, exchange students" keep us young-they really," said Jean Foster, who is hosting 16-year-old Nina Porst from Denmark.
Foreign teenagers come to American families with the purpose of ______.

A. finding their parents in America
B. Finding good jobs in America
C. learning the culture of America
D. enjoying the life of America