need,需要，-less,无，没有。

1. All this, needless to say, had been culled second-hand from radio reports.

不用说，所有这些都是从电台报道中采集来的二手材料。

2. "I have never knowingly exposed any patient to needless risks," he said.

他说：“我从未故意将任何病人置于不必要的风险境地。”

3. Needless to say, theory and practice sometimes diverged.

不用说，理论和实践有时候并不相符。

4. Banning smoking would save needless deaths.

禁止吸烟会免除不必要的死亡。

5. So much needless repetition makes the article long - winded.

这样叠床架屋,文章就太罗嗦了.