改正句子的错误括号内的为错误部分,请帮忙改正,1.It was (him) who did all the work o

改正句子的错误
括号内的为错误部分,请帮忙改正,
1.It was (him) who did all the work on the invention,but somebody else got all the credit.
2.The company's training plan was designed to help the employees improve (its) work habits and efficiency.
3.No matter how good my paintings are,i am conscious that they (may be having) unacceptable imperfections.
以下两题是我自己改的,请高手看下我改的对否.
4.After the automobile accident,the driver (wasn't) scarcely able to tell the police what had happened.----改为couldn't.
5.（Sinking before it got to the finish line）,the regatta race could not be fininshed,much to the regret of the boat's owner.---- 改为sinking before it reach the finish line.
谢谢朋友们的回答，现在就剩第5题不知道怎么改了！