I was surfing the internet the other day when I found this phrase: Instead your precious time and attention is wasted. To my ears, it sounds wrong. But I'm not a native English speaker, so I consulted with a number of them, and some of them said that it was "is" because the adjective modifies only the noun "time" and not "attention". Others said it "is" because that's just how it is. But I still believe it should be "are". Any help is appreciated. Thank you.
The claim about the influence of the adjective is misleading - the major question is whether time and attention are separate concepts or time and attention is a single composite concept. See at http://grammar.about.com/od/rs/g/Subject-Verb-Agreement.htm (under 'Agreement With Compound Subjects Joined by And')
Usually, there is a virtually idiomatic status with 'apparently plural assemblages treated as singular':
There are relevant hits for "time and attention is...":
but also for "time and attention are":
The concepts are inter-related and thus may be considered as a whole, but the words do not really constitute a fixed expression, and so may also be considered individually within the phrase.
Here is the rule nouns connected with AND. If the nearest noun is singular takes singular verb, and if the nearest noun is plural takes plural verb.