.There are many black clouds. It is _______ to rain again.
The factory ___ I am going to is the place ___ my mother used to work many years ago.
The last river __ _ they crossed is two miles wide.
This is one of the means ____t he electic energy is conducted from one place to another.
The buses, ____were already full, were surrounded by an angry crowd.
Can you solve such problems ___raised by the audience?