please say what is the error in these sentences

[gowri haribabu]

1.) alice is as old as his cousin brother
2.)it was not suprising of john to enquire after mary,his former wife.
3.)everyone mustn't be aiming to become an engineer,must he?
4.)iam old enough to be travelling alone,aren't i??
5.)all the guest signed their names in the visitors book which the manager kept in his office
6.)the vital force about labor added materially for the highest standard of living
7.)In 1909,the sunday preceding labor day was adopted as lobor sunday and dedicated to the spiritual and educational aspects
8.)high gasoline prices can be brought down if everyone does his or her part and pays for the gasoline they use at the pumps
9.)the storm reached its crescendo shortly before three a.m in the morning
10.)At the beginning of 1988 the world bank established a special internal audit commitee to examine problems of corrupyion in its lending policies

[5jj]

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