find the mistake
1- she isnt bad in working out sums
2-she insists in not marrying him even he is well- qualified
3- the murderer was well disappeared so the police took time to arrest him.
4-if you need help,will come and see me.
5- unless wars continue children will be left without parents.
6-had there more trees , the air we breath would be cleaner.
7-butfor having the power will ban all cars from city center.
8- .old hisham hgot itself married at last
9-. I gave him his book and took
10- .self-confidence students always do well in their exams
11- .have you waited for long before we sent an excuse

in-at in-on disappeared-hidden erase will unless-if had-were