将斜槽固定在水平桌面上，将滑块从斜槽的某一高度处无初速释放，测出滑块在桌面上滑过的距离 $x_1$ ；

将斜槽固定在桌子边缘，将滑块再次从斜槽上无初速释放，测出滑块落地点到斜槽末端的水平距离 $x_2$ ；槽末端到水平地面的高度h。

8月1日这个日子，曾于1933年被中共中央革命军事委员会定为中国工农红军成立的纪念日，后来又被定为中国人民解放军的建军节。这是为了纪念（    ）

请将植物组织的主要功能的序号填在相对应植物组织名称后的横线上．

a．有支撑和保护作用     b．保护内部柔嫩部分的功能

c．储藏营养的功能        d．分裂分化形成其他组织

A．保护组织____B．营养组织____

C．机械组织____D．分生组织____．

如图甲依次为桃的花、枝条和果实的结构示意图，请据图回答：

    I have a good friend in my class. His name is Jim. He is from England. He is in China with his parents. He likes China. He likes Chinese food very much. He has breakfast at home. He eats an egg. bread and milk for breakfast. He doesn't like fish. He has lunch at home. The lunch in his school is delicious. He can have different kinds of food for lunch. He eats rice, meat and vegetables. Sometimes he has noodles and dumplings. He has supper at home with his friends. Sometimes he goes out to eat with his friends. He has meat , vegetables and fruit for dinner.