根据语境，从方框中选择单词并用其适当形式填空.

bite ，flexible，income ，therefore ，tension ，tear ，operate ，whisper ，spill ，harm ，export ，assist

（1）The

spilt

spilt

coffee has left a mark on the table cloth.
（2）When reading her story，I was moved to

tears

tears

several times.
（3）I believe we all can learn a lot and gain great pleasure from

assisting

assisting

others.
（4）A team of nurses assisted the doctor in performing the

operation

operation

yesterday.
（5）The average

income

income

of Chinese people has largely increased in the past few years thanks to the rapid development of China's economy.
（6）Listening to music and doing exercise play an active role in reducing

tension

tension

.
（7）At no time should we do anything that will

harm

harm

the interests of our nation.
（8）It is reported that China

exports

exports

a lot of fruits and flowers to many countries every year.
（9）I must learn

to bite

to bite

my lip.
（10）A

flexible

flexible

object or material can be bent easily without breaking.
（11）She leaned over and

whispered

whispered

something in his ear.
（12）Then pollination（授粉） takes place，

therefore

therefore

increasing the chances of the survival of the plant species.