常用集成电路的封装方法有（）。
A.陶瓷双列直插
B.塑料双列直插
C.陶瓷扁平
D.塑料扁平
E.金属扁平
参考答案：A, B, C, D
．_________the fact that doctors have warned that smoking causes cancer, people still keep on smoking.
A．Due t o
B．Thanks to
C．In case of
D．In spite of
用完全互换法装配时、用（）法计算尺寸链。
