题目内容
【题目】在“探究小车的速度随时间变化的规律”的实验中,某同学操作过程中有以下实验步骤:
A.拉住纸带,将小车移至靠近打点计时器处,先放开纸带,再接通电源;
B.将打点计时器固定在长木板上,并连接好电路;
C.把一条细绳拴在小车上,细绳跨过定滑轮,下边吊着适当重的钩码,放手后看小车能否在木板上做平稳的加速运动;
D.断开电源,取下纸带;
E.把一端附有定滑轮的长木板平放在实验桌上,并使附有定滑轮的一端伸出桌面;
F.将纸带固定在小车尾部,并穿过打点计时器的限位孔;
G.换上新纸带,重复操作两次。
(1)其中有错误的步骤是____________;应改正为____________________。
(2)将改正后的步骤按合理的顺序写在横线上:
步骤顺序为______________。
【答案】(1)A 应先接通电源,再放开纸带 (2)EBCFADG
【解析】(1)打点计时器在使用时,为了使打点稳定,同时为了提高纸带的利用率,使尽量多的点打在纸带上,要应先接通电源,再放开纸带,故A错误。
(2)本着先安装器材,后进行实验的思路,如在该实验中,先固定长木板,安装打点计时器,准备完毕开始进行实验,注意要先打点后释放小车,做完一次实验要及时关闭电源,故正确的实验步骤是EBCFADG。
【题目】根据语境,用方框中所给短语的适当形式填空。(每个短语仅使用一次)
communicate with, more than, the number of, be based on, because of, be able to, make use of, such as, at present, come up |
1. Then each new student had to ________ to the front of the classroom and introduce themselves.
2. You don’t have to join in; there are ________ enough people on the job already.
3. ________ children under 14 are not permitted in bars.
4. If you speak English, you can ________ business people from other countries.
5. The reports ________ wrong information, so don’t believe it.
6. My friend tried to join the army but was refused ________ his poor health.
7. You have to type in commands, ________ "help"and"print".
8. This year we can even ________ buy many more presents for our grandchildren. It’s great.
9. Excuse me, can you tell me how you ________ your spare time?
10. ________ people asking to go there is on the increase.