1. I was involved in a traffic accident.
我遭遇交通事故了。
还能这样说：
A traffic accident happened on me.
I came across a traffic accident.
应用解析：
be involved in 包含在……；与……有关；被卷入；专心地（做）；
involve one's future 关系到某人的未来
2. We think the accident is the inevitable consequence of his habitual drunken driving.
我们认为这次事故是他经常酒后驾车的必然后果。
还能这样说：
We believe that his habitual drunken driving leads to the accident.
We think that because he often drives after drinking, the traffic accident happens on him.
应用解析：
answer for the consequences 对后果负责；
as a consequence 因而，结果；
face the consequences of one's action 自食其果
3. The police decided to inquire into the events leading up to the accident.
警方决定对这起事故的肇事原因进行调查。
还能这样说：
The police made a decision about the research on the reason of the accident.
The police decided to investigate the cause of the accident.
应用解析：
inquire into 盘查，调查；追究；
inquire out 问出，查出
4. The little boy's parents were killed in a traffic accident.
那小男孩的双亲在一次交通事故中丧生。
还能这样说：
The little boy's parents died in a traffic accident.
The little boy's parents lost their lives in a traffic accident.
应用解析：
have an accident 遭受意外；
meet with an accident 遭不测，失事；
without accident 平安无恙地；
by accident 偶然