下列物质属于纯净物的是 （ ）

如图反映的是（    ）

如图1所示，物体以一定初速度从倾角α=37°的斜面底端沿斜面向上运动，上升的最大高度为3.0m．选择地面为参考平面，上升过程中，物体的机械能E_机随高度h的变化如图2所示．g=10m/s²，sin37°=0.60，cos37°=0.80．则（   ）

根据短文理解，完成各题任务。
C
    Sally is an English girl. She is my English teacher, Mrs. Brown's daughter. She is only five years old. (A)She can't go to school. She likes playing ping-pong.
    Her favorite ping-pong player is Zhang Yining. Sally is in the ping-pong club. She goes to the ping-pong club every day. She plays ping-pong for two hours there.
    Sally has a sister. Her name is Maria. She is in our class. She likes running. She runs with her mother every morning. (B)她最喜欢的赛跑明星是刘翔. Maria says she wants to be a running star like Liu Xiang.

    Michelle Obama is the first lady of America. She visited China on March 20th, 2014. When she met the president Xi, she wore a red dress. She said her red dress is always ready for the important moment. Do you know she is also the first lady of fashion American?
    Every first lady since Lou Hoover (except Bess Truman) has appeared in the high-fashion magazine, Vogue. But Mrs. Obama is only the second to appear on the cover. She appeared wearing a pink silk dress by Jason Wu. When she was interviewed by the editor of Vogue, Mrs. Obama said what she wears is always paid attention to by many people. “I'm not going to pretend that I don't care about it.” she said. Most cover models have their clothes chosen for them by Vogue, or at least editors work as advisers. However, Mrs. Obama did choose outfits for the Vogue photos from labels(商标) she had worn before. “She doesn't need any help. She loves fashion and knows what works for her,” Talley said. “She's never had a conversation with me about, `What do you think?' or `How did this look?' And I'm glad for that.”