We work together to achieve our common purpose: _________ world that is safer, cleaner and healthier than __________ one we are living in.

He spent all his free time _____ the sick old man. [ ]

intelligent people can often _____ thecomplex, a fool is more likely to complicate thesimple.

The Dai people were celebrating the Water Festival, _____ they were having!

Such things ___ you described in the report seldom happen now.