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

When it comes to a foreign language, he is not ________ quick a learner as his brother.

As their memories decline, some old people tend to be talkative because they ______ forget what has just been said.

This is only a solution that can be adopted to solve the problem       , so you have to find a better way.

The incomes of skilled workers went up. ______, unskilled workers saw their earnings fall.