用方框中所给单词的适当形式填空

science；finish；act；be；help

【1】Mary wanted to be a singer when she _____ college.

【2】—How often does your sister take _____ lessons?

—Three times a week.

【3】What do you want ______ when you grow up?

【4】Mike and Grace _____ their mother with the housework tomorrow morning.

【5】The _____ has failed in the test many times，but he never gives up.