Suddenly it ____ me that if I let him go, he would never come back again.

.I don’t think that the sentence need ______again.

Another form of poem that teenagers like is the Tang Poem, a poem usually ________ four or more than four lines.

The scientist ______ much of his time to increasing the rice production.

—Have a good rest ; you need to ____ your energy for the football match this afternoon .—Thanks a lot .