They _______ all the details of the plan time and again to make sure that the project went smoothly.

 Mr. Liu born in a poor family, _____a lot of suffering when still a child.

Many single parents      with the dilemma of dividing time between work and children。

 If traffic moves at low speeds, the number of accidents is       .

When I ______to take part in the sport, I felt very surprised because I had never done this before.