关键词一：point to 指向；指着
1. While talking to us, the young man pointed to a policeman not far away.
那个年轻人跟我们说话的时候，指着不远处的一个警察。
2. He pointed to that oil painting and told us about its history.
他指着那幅油画，向我们介绍它的历史。
关键词二：explain v. 解释；说明
1. The young man explained why they stopped us.
那个年轻人解释人与人之间为什么拦下我们。
2. He explained the reason why he was made to catch the offenders.
他解释他被要求抓违章者的原因。
3. She explained that her bus hadn't come up on time.
她解释说她要乘坐的公交车没有按时到达。