The Klondike was the_____ of one of the biggest gold rushes the world has ever known.

Please refer to the   before you switch on the engine.

 — Do you have any plans for this holiday?— To tell you the truth, I have nothing in        for holiday.

With the address to help him he had no ____ in finding her new house.

This law which has just been passed is a that the government will pay more attention to protecting wildlife．