Jack, when shall we go to visit Mr. Smith? – It’s up to him. We’ll go to see him whenever _______.

woman is Tom’s mother? —–The one in the red coat．

Is the Youth Center open to the public yet?—Yes. It ______ for almost one and a half years.

You might as well expect a river to flow backward ____ us carrying out the plan.

When I got there, the train _____________.