Excuse me, sir. Here’s a letter for Liu Tao. Which room does he live in —–_____.

Which sentence is wrong?

It is the interaction between people, rather than the events __ occur in their lives, __ is the main focus of social psychology

Thank you so much for helping me with my English.— ________. That’s what friends are for.

In order to make Dandong more beautiful, more trees and flowers ________ every year.