阅读理解。 WASHINGTON - President Obama and his wife, Michelle, handed out Halloween treats to area children and military families at the White House Sunday evening. Local students between 6 and 14 years old, along with children from military families, were invited to celebrate Halloween on the North Lawn. The president and first lady, along with Mrs.Obama's mother, Marian Robinson, spent about 30 minutes passing out goodie bags.Obama wished each child a happy Halloween as he distributed the treats, pausing occasionally for hugs or to comment on costumes. Later, the military families continued the celebration inside the White House. The first couple joked to assembled reporters about children walking the long driveway in order to work off (消化掉) the snacks.'This is the Let's Move method of trick-or-treating (不给糖就捣蛋),' Obama said, referring to Mrs.Obama's campaign to combat childhood obesity (肥胖). The goodie bags contained a box of White House M&Ms, a cookie made by pastry chef (点心师) Bill Yosses, and dried fruit. As they made their way across the lawn, the children meet a vast range of costumed characters ranging from a spooky Frankenstein (科学怪人,小说《弗兰肯斯坦》的主角) to the Scarecrow from 'The Wizard of Oz .' Music from a jazz band dressed in pirate gear rang out across the White House grounds. Multicolored pumpkins and gourds lined the driveway - individually, in gravity-defying stacks and as part of a large mound over 5 feet tall.Pumpkin-headed scarecrows (稻草人) made of cornstalks loomed over the path with menacingly raised arms.Under the White House portico, a mobile resembling bats flying through clouds fluttered around a lantern. Some of the local trick-or-treaters were students at Bancroft Elementary, which helps tend the first lady's  White House garden, and Tubman Elementary, which has a relationship with the White House chefs. After trick-or-treating ended, the Obamas stood near the front door, welcoming the military families inside, helping children climb the short flight of steps and thanking parents for their service. 1.What is the news report mainly about? A. President Obama and first lady celebrated Halloween with children. B. President Obama and his wife Michelle handed out Halloween treats to children. C. Children from military families were invited to celebrate Halloween at the White House. D. Trick-or-treaters met a vast range of costumed characters from Frankenstein to the Scarecrow. 2. From the passage, we know that ______ do not necessarily appear when people celebrate Halloween. A. Goodie bags B. Pumpkins and Gourds C. White House M&Ms D. Costumed characters 3.When celebrating Halloween at the White House, the Obamas did the following EXCEPT______. A. Wishing each child a happy Halloween B. Thanking reporters for their covering the event C. Helping children climb the short flight of steps D. Hugging children and commenting on their costumes 4.The passage is mainly developed by ______. A. analyzing causes B. making comparisons C. examining differences D. following the time order