有止血和加速凝血作用的是（　　）

实验室中需要22.4L（标准状况）SO₂气体．化学小组同学依据化学方程式Zn+2H₂SO₄（浓） $\frac{\underset{\_}{△}}{}$   ZnSO₄+SO₂↑+2H₂O计算后，取65.0g锌粒与98%的浓H₂SO₄（ρ=1.84g•cm^﹣3）110mL充分反应锌全部溶解，对于制得的气体，有同学认为可能混有杂质．

一段导体两端的电压是24V时，通过它的电流是0.6A，则导体的电阻是____Ω，当导体两端的电压是12V时，此导体的电阻是____Ω.

阅读短文，判断正误。
    Hello, friends! Let's go on a trip to Beijing. Beijing is the capital city of our country. It's in the north of China. There is a big square in this city. Do you know its name? Its name is Tian'anmen Square. In Beijing, you can see the Bird's Nest(鸟巢). The 2008 Olympic Games were held in it. And you can see some old buildings, such as the Palace Museum. The Great Wall is also very famous in China. It's very old and long.

实验中用同一显微镜观察了同一装片4次，得到清晰的四个物像如图．有关该实验的说法不正确的是（　　）