烟叶分类是依据烟叶的调制方法、（）和用途对烟叶所进行的类别划分。

可以用于检测前房深度的仪器是（）。

A.计算机辅助角膜地形图分析系统

B.Orbscan角膜地形图系统

C.角膜曲率计

D.角膜内皮镜

E.房角镜

Because the process of freezing food consumes energy, many people keep their electric freezers half-empty, using them only to store commercially frozen foods. Yet freezers that are half-empty often consume more energy than they would if they were kept fully stocked.
Which of the following, if true, contributes most to an explanation of the apparent discrepancy described above ？（）

A．A given volume of air in a freezer requires much more energy to be maintained at a temperature below freezing than does an identical volume of frozen food.

B．The more often a freezer’s door is opened, the more energy is required to maintain that freezer’s normal temperature.

C．When unfrozen foods are placed in a freezer, the average temperature of a given volume of air inside that freezer rises temporarily.

D．A person who normally maintains a half-empty freezer can cut energy costs considerably by using a freezer that is 50 percent smaller.

E．An electric freezer can operate efficiently only if chilled air is free to circulate within the freezing compartment.

施工项目成本控制是以( )为依据。

A．成本预测

B．成本计划

C．成本核算

D．成本分析

改扩建工程，在运行区内作业，开工前应做哪些准备工作（区别新建工程）？