We need a clear understanding of the problems involved.
我們需要了解清楚所涉及的各種問題。
This research has done much to advance our understanding of language learning.
這項(xiàng)研究大大提高了我們對(duì)語(yǔ)言學(xué)習(xí)的認(rèn)識(shí)。
Stop fussing around and find something useful to do!
別瞎忙活了，找點(diǎn)有用的事干！
Your local library will be a useful source of information.
你們當(dāng)?shù)氐膱D書館就是很好的資料來(lái)源。
It's a useful introduction to an extremely complex subject.
這是對(duì)一門極為復(fù)雜的學(xué)科的有益入門教程。