The government has been under growing pressure to ________ the causes of air pollution as smog frequently smothers the country’s large cities.

You should write a _____________ composition every other week.

I tried to ______ Tom last night, but no one answered the phone.

He didn’t _____ to what I said because his mind was on something else.

(2013·湖北，21)Poetry written from the________of the urban youth tends to reveal their anxiety over a lack of sense of belonging.