It is not always easy for thepublic to see _____ use a new invention can be of to human life.

When she feels ________, I talk to her and make her happy.

The scientist won the Nobel Prize in Chemistry, ________ made him famous all over the world.

In order _______ his English，he joined an English club.

of the keynurotransmitters influencing our mood, and ________it helps to relieve mooddisorders