Sometimes people seem frustrated because they have to remember to use commas with coordinating conjunctions and semicolons with conjunctive adverbs most of the time. If you can't keep the difference straight in your head, it can help to remember that commas are smaller than semicolons and go with coordinating conjunctions, which are almost always short two- or three-letter words—small words, small punctuation mark.

So it was particularly jarring to drive straight from the school to the West Bank to see the Jewish settlements that have become a flashpoint of the stalled peace process. The security wall. The roadblocks and barbed wire. The separate roads that the Palestinians have to use. The checkpoints and "buffer zones." The very large, sprawling, and very permanent-looking Israeli settlements carved out on Palestinian land. No wonder Palestinians feel like strangers in their own land.

But the newly obtained documents show that Dr. Carlin’s highly skeptical views on global warming, which have been known for more than a decade within the small unit where he works, have been repeatedly challenged by scientists inside and outside the E.P.A.; that he holds a doctorate in economics, not in atmospheric science or climatology; that he has never been assigned to work on climate change; and that his comments on the endangerment finding were a product of rushed and at times shoddy scholarship, as he acknowledged Thursday in an interview.

In his real life Jay-Z comfortably does grown-up things: organizing and performing at a 9/11 charity concert at Madison Square Garden last Friday; playfully parrying marriage questions from David Letterman; delivering well-honed therapy-speak in an interview with Oprah Winfrey for her magazine; attending a Grizzly Bear show.