The great theme was at Prescotts disposal. In order to feel sure-footed in the language, he went over his Spanish grammar again. Then he began to read all round the subject. Beginning with the general laws of nations, the constitutional history of England, the histories of the continental countries, France, Italy, Germany, Portugal, the general history of Spain, before he settled on his special field.請(qǐng)教一下專家老師，紅色部分的句子結(jié)構(gòu)是否有問題�。窟@是主句被簡化了么？

紅字部分為一個(gè)beginning目前分詞短語和一個(gè)before時(shí)間狀語從句，都是前面這個(gè)句子Then he began to read all round the subject. 的狀語。beginning應(yīng)小寫，前面的句號(hào)改為逗號(hào)。