A．让小球多次从斜槽上的   ▲    （相同/不同）位置滚下，在一张印有小方格的纸上记下小球碰到铅笔笔尖的一系列位置，如图中所示的a、b、c、d. 

B．按如图安装好器材，注意斜槽末端保持  ▲  ，记下平抛初位置O点和过O点的竖直线．

C．取下白纸以O为原点，以竖直线为y轴建立平面直角坐标系，用平滑曲线画出小球做平抛运动的轨迹.

下列句子有错别字的的一项是（ ）。

观察口腔上皮细胞临时装片时，我们看到细胞中染色最深的是（  ）

根据句意，从方框中选择合适的单词或短语，并用其适当形式完成句子。                      

(1)Designs for the new gym will be ____  in the library. 
(2)Jim ____  his father. They are both clever and a bit quiet.
(3)I was waiting for the school bus but it didn't come. Then I ____  it was Saturday.
(4)Beijing is cold this time of year. You need to ____ warm clothes if you go there.
(5)Don't forget to ____  the door if you are the last one to leave the classroom.