I couldn't hear what they were saying.

我听不见他们在说些什么。

《牛津词典》

I could hear voices but I couldn't make out what they were saying.

我能听到说话的声音，却听不清他们在说什么。

《牛津词典》

I wish I knew what they were driving at.

我要是知道他们的用意就好了。

《牛津词典》

Rates of breast cancer in Japan, Singapore and South Korea are now three times what they were forty years ago.

VOA: special.2009.03.02

Or whether or not they had no idea what they were doing, and they've given themselves over to this process.

还是说诗人并不完全理解自己写的文字，而是在创作过程中完全超然忘我。

普林斯顿公开课 - 人性课程节选

I've passed through Grand Central Station when filming was happening. I don't know what they were filming though.

有一次我从那儿经过，正好有部电影在拍。但我不知道他们在拍什么电影。

电影里的中央车站 - SpeakingMax英语口语达人

The division needed someone who sounded like they knew what they were doing, Packard recalls.

FORBES: The sweet smell of oil

Total salaries for Bulls players are only 47% of what they were during the Jordan era.

FORBES: Score!

"We were looking for artists who were passionate about what they were doing, " Mr. Alpert says.

WSJ: Cultural Conversation: Herb Alpert