_______ he was 12, Einstein had learned advanced mathematics by himself.

A．As soon as

B．At the time

C．By the time

D．During the time

现代政党区别于其他社会政治组织的最重要特征是( )

A．具有明确的政治目标

B．拥有明确的政治纲领

C．健全的组织系统

D．规定了一定的组织纪律