It is reported that in our country cities __________ heavy air pollution that is 30 percent above the national standard or higher should try to meet standards by 2030.
Human beings are different from animals _______ they can use language as a tool to communicate.
______ is often the case with elder people, my grandma talked about my new hairstyle for at least 50 minutes nonstop.
Eugene’s never willing to alter any of his opinions, so it’s no use ________ with him.
Charlie ______ be really difficult at times even though he’s a nice person in general.
It was only after I came across that matter_______ how important it was to master a foreign language.