____is known to all, good friends _________ happiness and value to life.
Although he lived ____ in a ____ mountain village, he didn’t feel ____ at all.
Our teacher told us that there ______ no end to learning.
In China, the number of cities is increasing _____ development is recognized across the world.
Please _____________ . The class is too noisy.
Currently, some overseas universities are simply selling diplomas to Chinese students ________ their academic performance, so China should check on a regular basis.