All too often, a choice that seems sustainable(可持续的)turns out on closer examination to be problematic. Probably the best example is the rush to produce ethanol(乙醇) for fuel from corn. Corn is a renewable resource —you can harvest it and grow more, almost limitlessly. So replacing gas with corn ethanol seems like a great idea. 

    One might get a bit more energy out of the ethanol than that used to make it, which could still make ethanol more sustainable than gas generally, but that's not the end of the problem. Using corn to make ethanol means less corn is left to feed animals and people, which drives up the cost of food. That result leads to turning the fallow land –including, in some cases, rain forest in places such as Brazil—into farmland, which in turn gives off lots of carbon dioxide (CO) into the air. Finally, over many years, the energy benefit from burning ethanol would make up for the forest loss. But by then, climate change would have progressed so far that it might not help.

    You cannot really declare any practice “sustainable” until you have done a complete life-cycle analysis of its environmental(环境的) costs. Even then, technology and public keep developing, and that development can lead to unforeseen and undesired results. The admirable goal of living sustainably requires plenty of thought on an ongoing basis.

    If you love to read, and if you love social networking, you should check out Goodreads. Goodreads allows you to write reviews（评论）for everything you've ever read. You can see and comment on your friends' reading progress, as well as create or find a book club group page in your area.

    Goodreads is simple to use. When you sign up here for an account（帐户）, you will be able to find your friends by their email addresses or other accounts. Once you have some friends, every time you log in（登录）, you will see a timeline of their updates. You can see when they've added a book to a list, or when they've finished or reviewed a book. As soon as you have an account, you can also start looking for books you've read or that you want to read. Once you finish reading a book, you can go to the book page and review it.

    Finding your next book has never been easier. Now, not only can you search for books you know you want to read and add them to your “to read” list, but you can also easily see what your friends have recently read.

    If you are looking for a book club that meets in your area, you can search for that on Goodreads, too. Similarly, if you want to create your own book club, you can do that easily: just start a new group on Goodreads and update the page to show what books you're reading.

    June 8

    Culinary (烹饪的）Historians of Washington: Food historian Joel Denker discusses how certain foods acquired culinary significance and ceremonial and economic importance. 2-4 pm .Free. Bethesda-Chevy Chase Regional Services Center, Meeting Room A，4805 Edgemoor Lane，Bcthcsda. 202-487-6740.

    June 11

Beers of Umbria: Beer director Scott Weiss leads a tasting of Italian beers. 7:30 pm. $35, Via Umbria, 1525 Wisconsin Avenue. NW. 202-333-3904.

    June 13

    Wine Dinner: A special menu paired with sparkling (气泡的）wine. 6:30 pm. $75, not including tax and gratuity (小费).Wildfire. Tysons Galleria. Third Floor. 1714 International Dr., McLean. 703-442-9110.

    June 14

    Cooking Class: Chef Gerard Pangaud demonstrates (展示) how to make several seasonal French dishes.11 am-2 pm. $85. Hill Center at the Old Naval Hospital, 921 Pennsylvania Avenue. SE. 202-549-4172.

    Hot Drinks from Around the World: Participants learn about and sample drinks made from purple com. yak (牦牛) butter, orchid root and more. 10 am. $27. Green Spring Gardens, 4603 Green Spring Road, Alexandria.

    June 18 pm-地 Columbu

    Gourmet Symphony: A special American cuisine-inspired menu accompanied performance by the Inscape Chamber Orchestra. VIP option available.7-9 pm. $49 Columbia Firehouse, 109 S. Saint Asaph St, Alexandria.

    June 28

    Sips: Cocktail reception featuring local artisans (技工）and mixologists (调酒师) benefit D.C. Central Kitchen and Martha's Table. VIP tickets also availabi 7:30 pm. $125 by

    June. 11；$150 thereafter. Newseum, 555 Pennsylvania Ave.NW.

    June 29

    Suppers：Fundraising dinners taking place in more than 35 area homes, featuring chefs Alon Shaya,Carla Hall,Tim Ma,

    Amy Brandwein and more. Proceeds benefit D.C. Central Kitchen and Martha's Table.6 pm. $600.

    THREE years ago Jenny Salgado, a Dominican shop assistant, moved to Highland town, a neighborhood of Baltimore. When she arrived the shop she works in, it was one of only a few Spanish businesses. Now there are many more. "It's good now if you speak Spanish," she smiles.

    Baltimore has been losing people for 60 years. To address this, its mayor, Stephanie Rawlings-Blake, wants to make it the most immigrant-friendly city in the world. Its libraries provide Spanish-language exercise classes. To help those with no papers, the city is introducing micro-loans (小额贷款) which require no credit checks; city police would no longer routinely check the immigration status of citizens or enforce any federal immigration law unless required to. The then governor, Martin O'Malley made it possible for illegal immigrants to get driving licenses.

    Such welcoming policies are spreading. Such cities as Cleveland, Dayton and Philadelphia all eagerly try to please immigrants. Rick Snyder, the governor of Michigan, has asked the federal government to offer 50,000 visas to people who agree to live in Detroit. His administration has made it easier for skilled migrants to get professional licenses.

    When a city's population falls, both tax receipts and services fall. Half-deserted neighborhoods breed (滋生) crime, driving yet more people to leave. No city has escaped this death circle without attracting new residents, says Steve Tobocman of Global Detroit.

    Several studies suggest that when immigrants arrive, crime goes down, schools improve and shops open up. In Detroit, immigrants living near the tiny separate city of Hamtramck have formed local watches to guard against thieves. Their neighborhoods are not just safer; they are also among the only places where it is as easy to buy fresh vegetables as drugs and alcohol.

    But attracting new immigrants to the cities which most need them is hard, argues Audrey Singer of the Brookings Institution. They care about the same things as everyone else: safe streets, good schools and jobs. Cities which have lost population for decades struggle with all of these.

    Welcome to SummerCamps.com; find and book the very best summer camps. Your children are precious so we offer the highest quality of camps that will meet each child's needs and interests.

    Catalina Sea Camp

    Sea Camp offers three one-week sessions to boys and girls aged 8-13 and two three-week sessions to teens aged 12-17. Our hand-picked instructors create an atmosphere of fun and excitement while leading campers to a host of ocean adventures, marine(海洋的) biology, and social summer camp activities.

    Address: Toyon Way, San Bruno, California 94066

    Phone: 800-645-1423

    Camp Cayuga

    Camp Cayuga is a private summer camp for children aged 6 to 16. The camp is on a 350-acre land in the Pocono Mountains of Northeast Pennsylvania, just outside the village of Honesdale. It's a 3-hour drive from New York City and Philadelphia.

    Address: 321 Niles Pond Road-Suite ISC, Honesdale, Pennsylvania 18431

    Phone: 908-470-1224

    Camp Rockmont

    Camp Rockmont is a Christian summer camp for boys, aged 6-16, in the Blue Ridge Mountains of North Carolina. Rockmont's duty of developing boys into healthy young men is accomplished through age-appropriate skills, activities, and challenges that help campers to know themselves better.

    Address: 375 Lake Eden Road, Black Mountain, North Carolina 28711

    Phone: 828-686-3885

    Primitive Pursuits Overnight Camps

    Primitive Pursuits Overnight Camps offer week-long Summer Adventure Overnight Camps in New York's Finger Lakes to your children aged 11-15. Campers experience a week of nature-based skills training, inspiring challenges, and fun activities under the guidance of skilled instructors.

    Address: 611 County Rd 13, Van Etten, New York 14889

    Phone: 607-272-2292