30. Only those who have experienced hardship ____ well aware of what happiness means.
QQ, ________you can chat with your friends, makes communication easy.
-----What do you think of the play ? -----Terrible! I have never seen________one.
I regret _____ more time with my grandma before she passed away.
. Do you know________there is a small river for us to swim in?
They want to employ 90 people, ________ last year.