西藏以藏族为主体,有藏、汉、回、门巴、珞巴、纳西等40多个民族。1965年9月,西藏自治区正式成立,西藏开始全面实行民族区域自治制度。西藏在***领导下,经过波澜壮阔的社会主义革命、社会主义建设和改革开放,逐渐从黑暗走向光明、从落后走向进步、从贫穷走向富裕、从专制走向民主、从封闭走向开放,走向了幸福美满的新生活。无论国际风云如何变幻,无论前进道路上遇到多少艰难险阻,西藏各族人民始终同祖国同呼吸、共命运、心连心,坚决维护祖国统一和民族团结。在中央的特殊关心和全国人民的大力支援下,西藏经济社会实现跨越式发展,经济总量翻了上百倍,创造了短短50年跨越几千年的人间奇迹。

阅读下列材料：

“渺茫天际，水天一色，舟舶来往，惟以指南针为则，昼夜守夜唯谨，毫厘之差，生死攸关。”

请回答：

某商场购进一批服装，每件进价为1000元，由于换季滞销，商场决定将这种服装重新标价后按标价的7折销售．若想打折后每件服装仍能获利5%，该服装的标价应是（   ）

如图，在四棱锥P﹣ABCD中，底面ABCD是菱形，且∠DAB=60°．点E是棱PC的中点，平面ABE与棱PD交于点F．

（Ⅰ）求证：AB∥EF；

（Ⅱ）若PA=PD=AD，且平面PAD⊥平面ABCD，求平面PAF与平面AFE所成的锐二面角的余弦值．

根据材料内容，选择正确答案。

    Jim, a young farmer, was once put into prison (监狱).

    One day, he got a letter from his mother. "I'm so worried about our farm," she wrote. "It's time to plant potatoes. I can't dig(挖) all the fields by myself. "

    Jim read the letter and became sad. "What can I do?" he thought. Then he had a good idea. He wrote to his mother, "Don't dig the fields. There's a pot of money in the earth. Don't plant potatoes until I come home."

    Some days later, Jim got another letter from his mother. It said, "Two days ago, about ten men came to our farm and dug all our fields. I can't understand it. It looks as if they were looking for something. What shall I do?"

    Jim smiled when he read his mother's letter. He wrote a letter to his mother at once. It was very short. Guess what it would say?