为了获得单链标记的DNA探针可以采用以下三种方法：______、______和______。
参考答案：M13载体 反转录 不对称PCR
. Tony was very unhappy for _______ to the party.
A．having not been invited
B．not having invited
C．having not invited
D．not having been invited
便利店一般无管理信息系统或具备初级信息管理系统。
