问题 单项选择题

根据沉降公式(Stocks方程)计算所得的直径称为

A.定方向径
B.等价径
C.体积等价径
D.有效径
E.筛分径

答案

参考答案:D

解析: 本组题考查粉体粒子大小的表示方法。
粒子大小的常用表示方法有:(1)定方向径:即在显微镜下按同一方向测得的粒子径。(2)等价径:即粒子的外接圆的直径。(3)体积等价径:即与粒子的体积相同球体的直径,可用库尔特计数器测得。(4)有效径:即根据沉降公式(Stocks方程)计算所得的直径,因此又称Stocks径。(5)筛分径:即用筛分法测得的直径,一般用粗细筛孔直径的算术或几何平均值来表示。

阅读理解

根据短文内容,选择最佳答案。

Every country has its own way of cooking. American people have their way of cooking, don’t they?

Most people in the United States like fast food, but if you think that American people don’t like cooking, you are wrong. It’s true that most Americans eat fast food for their breakfast and lunch, but they also think cooking is interesting. Parents see the importance of teaching their children how to cook, and most Americans say that home cooked meals are the best.

Americans have their own way of cooking. For example, baking  (烘烤) is the most popular way of cooking in America. Most American families have ovens. American cooks pay attention to (注意) the balance of food. In planning a big meal, they try to cook meat, a few vegetables, some bread and often some sweet food. They also like to make the meal look beautiful. There are many kinds of food of different colors, so the meal is healthy and looks beautiful, too.

小题1:Most Americans       

A.don’t like cooking

B.cook food in the morning

C.eat fast food

D.like having a picnic小题2:Most Americans       

A.don’t eat fast food for their breakfast or lunch

B.have fast food for their breakfast or lunch

C.like to eat fast food for supper

D.don’t have breakfast or lunch小题3:        is the most popular way of cooking in the USA.

A. Baking             B. Cutting        C. Frying      D. Boiling

小题4:How does an American cook balance different kinds of food?

A.He cooks a lot of meat.

B.He cooks meat, vegetables, bread and sweet food for a big meal.

C.He makes the food delicious.

D.He cooks a lot of vegetable.小题5:Which is right according to the passage?

A.The meal looks beautiful because the food is in different colors.

B.American people do not like to cook food at home.

C.American parents do not like to teach their children to cook.

D.Most people in the United States don’t like fast food at all.

填空题