Find which one word cannot be made from the letters of the given word: $TEACHERS$.

If it is possible to make a meaningful word with the fourth,the seventh,the eleventh and the thirteenth letters of the word $CATEGORISATION$,which of the following will be the first letter of that word? If no such word can be made,give $X$ as the answer. If more than one such word can be made,give $M$ as the answer.

Find which one word cannot be made from the letters of the given word: $SIGNIFICANT$.

Find which one word cannot be made from the letters of the given word: $COLLABORATION$.

If it is possible to make only one meaningful word from the second,the third,the sixth and the eighth letters of the word $DEVIATION$,the first letter of the meaningful word is your answer. If more than one such word can be formed,your answer is $A$,and if no such word can be formed,your answer is $B$.

How many such pairs of letters are there in the word $DOCUMENTARY$,each of which has as many letters between them in the word as there are between them in the English alphabet?