在硅片制造中光刻胶的两种目的是什么？
参考答案：
一，将掩膜版图案转移到硅片表面顶层的光刻胶中
二，在后续工艺中，保护下面的材料
( )的测定是概率分析的关键，也是概率分析的基础。
A．风险因素概率分布
B．风险因素变量分布
C．评价指标的分布
D．风险因素定级
The pilot of a small aircraft with a 40-gallon fuel tank wants to fly to Cleveland, which is 480 miles away. The pilot recognizes that the current engine, which can fly only 8 miles per gallon, will not get him there. By how many miles per gallon must the aircraft’s fuel efficiency be improved to make the flight to Cleveland possible ？（）
A. 2
B. 4
C. 12
D. 40
E. 160
