(I) Directions: Translate the following sentences from English into Chinese (4 points each for NO.66 through NO.68; 6 points for No.69; 18 points in all )

　　66.Sound travels four times faster in water than in the air.

　　67.It was not until you told me about it yesterday that I realized my mistake.

　　68.China will be the largest market for automobiles if its economy continues to grow.

　　69.I find it hard to leave the land where I have lived for 30 years and where there are sweet memories of my childhood.

　　(II) Directions: Translate the following sentences from Chinese into English (4 points each for No.70 through No.72; 5 points for No.73; 17 points in all.)

　　70.我反复尝试，终于得到了一份工作。

　　71.没过多久，房子外面就聚集了很多人。

　　72.这家工厂里的所有机器都是中国制造的。

　　73.我不满意那家旅馆的服务，因此要向旅馆经理投诉。