某动物体腔内有膈,生活在水中,是我国特有的珍贵动物,该动物是( )
A:扬子鳄
B:大鲵
C:大熊猫
D:白鳍豚
A
⑴Who are they? ____
⑵Where did you live?____
⑶Is this your grandpa?____
⑷Did he learn Chinese ?____
⑸What's he doing?____
B
A.Yes, it is.
B.They are my grandparents.
C.He's reading a book.
D.No,he didn't.
E.I lived in a small house.
某同学用图1示的实验装置探究加速度与力的关系.他在气垫导轨旁安装了一个光电门B,滑块上固定一遮光条,滑块用细线绕过气垫导轨左端的定滑轮与力传感器相连,力传感器可直接测出绳中拉力大小,传感器下方悬挂钩码.改变钩码数量,每次都从A处由静止释放滑块.已知滑块(含遮光条)总质量为M,导轨上遮光条位置到光电门位置的距离为L.请回答下面相关问题.