制作洋葱鳞片叶表皮细胞临时装片时，必须让盖玻片的一侧先接触液

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问题选择题

制作洋葱鳞片叶表皮细胞临时装片时，必须让盖玻片的一侧先接触液滴，然后再缓缓地盖上，其目的是（　　）

A．增强装片的透明度

B．防止水溢出污染装片

C．避免实验材料移动

D．避免盖玻片下出现气泡

答案

制作临时装片时，必须让盖玻片的一边先接触水滴，再轻轻盖上，目的避免盖玻片下出现气泡，影响观察效果．

故选D．

阅读理解

阅读短文填空。

Look at this picture. It's our house. Some hills are near the house. There is (有) a big tree here

in front of the house. A bird (鸟) is in the tree. My brother's cat (猫) is under the tree. Its name is

Tom. There is a lake behind the house. A boat is on the lake now. In the boat there is a girl. That's

my sister. Her name is Kate. Her dog is in the house.

1. A bird is in the _____ .

2. The _____ is under the tree.

3. A _____ is in the boat.

4. My sister is _____.

5. The cat's name is_____.

解答题

（0.12+0.23+0.34）×（0.23+0.34+0.45）-（0.12+0.23+0.34+0.45）×（0.23+0.34）=______．