下图表示制作洋葱鳞片叶表皮细胞临时装片的有关实验步骤，正确的顺序是（    ）

如图所示为某人横渡长江的照片，图中他以一定速度面部始终垂直于江岸向对岸游去．设江中各处水流速度相等，则他游过的路程、过江所用的时间与水速的关系是(    )

已知矩形ABCD的对角线AC与BD相交于点O，如果 $\stackrel{\rightharpoonup }{BC}$ = $\stackrel{\rightharpoonup }{a}$ ， $\stackrel{\rightharpoonup }{DC}=\stackrel{\rightharpoonup }{b}$ ，那么 $\stackrel{\rightharpoonup }{BO}$ 等于（   ）

用动词的适当形式填空。
⑴In class, every student in our class ____  (take) notes carefully
⑵–Do you think whether the book called Harry Porter is worth ____  (read)?  - Yes, of course.
⑶ I called you yesterday afternoon, but you were out. - Oh, I ____ (watch) a football match on the playground.
⑷ Can you hear the two boys ____  (argue) with each other right now?
⑸The person we talked about ____  (visit) our school next week..

下列我们生活中的现象与地球自转无关的是（    ）