Hidden _____ by a big tree, his house was not to be seen.

A．as it was

B．as it is

C．as it did

D．as he did

阅读《行路难》（其一），回答问题：

金樽清酒斗十千，玉盘珍羞直万钱。停杯投箸不能食，拔剑四顾心茫然。欲渡黄河冰塞川，将登太行雪满山。闲来垂钓碧溪上，忽复乘舟梦日边。行路难，行路难，多歧路，今安在？长风破浪会有时，直挂云帆济沧海。

这首诗表现了诗人怎样的思想矛盾？