二极管只具有反向阻断能力，而晶闸管则具有正反向阻断能力。
参考答案：对
―Why didn't you go to the party last night?
―Because I _______. [ ]
A. wasn't invited
B. didn't invite
C. haven't invited
当有很大把握预测牛市到来时，应选择那些卢系数低的证券或组合。( )
