绝对不能使用绝缘发空的办法来降低介电系数，因为这会引起内部电晕而降低介电强度。( )
参考答案：对
各企业之间的竞争战略越相似，彼此之间的竞争就会越平淡。( )
It is said that more than two hundred students have ______ the discussion. [ ]
A. joined
B. joined in
C. joined to
D. joined up
