One’s life has value _____ one brings value to thelife of others.

I have two children， and ______ of them are working in the west of China.

Oh, boy, why are you killing yourtime this way? Can’t you find something _____ doing? [ ]

She was too busy ______ at that time with me. I was unhappy about that.

The writer ___ his writing so that heforgot to have his lunch.