The invention of steam engine greatly sped up the industrial revolution, which ________ a lot to the take-off of the world.

 I will treasure the encounter with the famous director who may ______my life. 

When my grandfather retired(退休) at the age of 60, he took a sea ________ around the world, which had been his dream since his childhood.

They must be working      because they have a lot of work to do yesterday.

 There are 5 star fathers in the TV program Dad, Where are we going, the Olympic Champion Tian liang ________.