肯定是不能改成having earning a doctorate的,因?yàn)闆]有having earning這種表達(dá)結(jié)構(gòu).
我猜想,你是想改成having earned?
其實(shí)原句的主干是：German chancellor AM was initially drawn to the sciences and earned a doctorate.
顯然,was drawing to 和earned是并列關(guān)系；如果要改寫后面的earned,自然是改成earning.
你想改成having earned,應(yīng)該是被你的中文翻譯所困擾（進(jìn)入政界以前,已經(jīng)獲得物理學(xué)博士學(xué)位）；如果按照你這種思路理解,是不是要將German chancellor AM was initially drawn to the sciences改為German chancellor AM had initially been drawn to the sciences呢?
所以沒必要改成having earned.啊，打字太急打錯(cuò)了。。。Thanks a looot!!!解釋超好~~