1、专营
... to speak volumes：含义很深，很有意义 to specialize in：专门研究;专营 to speculate on：思索;推测，猜测 ...
2、专门研究
...to speak volumes：含义很深，很有意义to specialize in：专门研究；专营to speculate on：思索；推测，猜测 ...
3、专攻
... 指令码插入式攻击 script injection attack 专攻 to specialize in; to major in 字典攻击 dictionary attack ...
4、专精
... commercial (adj.) 商业的；商用的 to specialize in 专精；专长 in the clear 不犯法；清白 ...
to specialize in English专修英语
learning to specialize in学有专攻
to specialize into major in专攻