I. The central question

Chapter 4 is about Su Tungpo and his father and brother went to take their examinations. The journey went to the capital is essential to their career life. Before Su Tungpo and his brother first went to Chengtu, they both settled marriage problem. From this examination, Su Tungpo meet Ouyang Shui and Mei Yaochen which have great effect on his literature character and career life. The other thing is Su Tungpo's mother died. When they heard this news, they set out for home. After that the Sus family moved to Kaifeng and start their official careers.

II. The sentence

1. The time of the civil service examinations was also the busy season of the matrimonial market. It was far preferable, from the parents' point of view, to have their sons married to girls of their own town, born of families they knew.

matrimonial    concerning marriage or married people

preferable    better or more suitable  "it was far preferable" 更好的是……

2. All marriages, however arranged, are a gamble and an adventure upon an uncharted sea.

uncharted    not marked on any maps

将婚姻的缔结比喻为赌博，以及在未知的大海中的探险，比喻非常精妙

3. All marriages are contracted in heaven but made on earth and by the men and women who have to make it after they come away from the altar.

这一句将上天注定的姻缘、男女缔结的婚姻，以及神圣的婚姻仪式三者非常精炼地融合在一句之中。姻缘天定，而由世间男女结合，并且通过圣坛中的仪式得以圆满。

4. Armed with these letters to Ouyang Shiu and Mei Yaochen, the father and sons went up to the capital by a land journey of over two months.

armed with these letters   十分形象地还原了三苏手持书信赴京的情景，armed强调了句首的书信，足见这些书信对三苏的举荐而言意义重大。