[3]headlong adj.&adv.=headfirst 头先向前的；轻举妄动地，匆匆忙忙地：He’s gone headfirst into trouble.他轻率地陷入麻烦中。

[4]dogged adj.顽强的，坚忍不拔的：She was not very clever, but by dogged efforts she learnt a good deal at school.她不怎么聪明，但努力不懈，在学校学到了很多东西。