Probability is the mathematical study of the _____ of an event's occurrence.
The students expected there ________ more free time before the test.
Does the way you thought of ________ the water clean make any sense?
The bridge is so important to the people here that once ________ it must be carried out without delay.
They tried to prevent the damage ________ their cattle.
His father disappeared, ________ two children and never _______ from again.