I have $50, but that isn’t ____ enough for my journey fare.

One thing that most organically grown food products seem to have in common is that they cost more than ________ grown foods.

—Must I turn off the gas after cooking ? —Of course . You can never be _______ careful withthat.

I hate interruptions, _____when I ’m concentrating on my study.

With the word“PM2．5"_____ appearing in media reports，people pay greater attention to it and seek health tips for smoggy days．