1、I remember those halcyon days of my childhood, when life was carefree and simple.
我记得我童年时那些宁静无忧的日子，生活是无忧无虑、简单纯真的。

2、The tropical island is known for its halcyon weather and crystal-clear waters.
这个热带岛屿以其宁静无忧的天气和清澈的海水而闻名。