The researchers found clear and convincing evidence _________ happiness is the key when it comes to better health and longer lives.

.Everyone in the village is very friendly. It doesn’t matter ___ you have lived there for a short or a long time.

They held a meeting ____ they could hear everyone’s idea.

In some places in Yunnan, women are expected to run society and earn money ______ men work at home and raise their children.

Please call my secretary to arrange a meeting this afternoon, or ________ it is convenient to you.