The probability of any event cannot be ..........

The probability of the month of April in any year having $5$ Sundays is ......... (in $/7$)

Two dice are numbered $1, 2, 3, 4, 5, 6$ and $1, 1, 2, 2, 3, 3$ respectively. They are thrown and the sum of the numbers on them is noted. Find the probability of getting each sum from $2$ to $9$ separately.

Chits numbered from $1$ to $120$ are put in a box and a chit is drawn randomly from the box. The probability that the chit drawn bears a $3$-digit number is ............

If a number is selected at random from one-digit natural numbers,the probability of that number being a multiple of $3$ is ..... .

If $P(\overline{B}) = 0.81$,then $P(B) = \ldots$