1. (2020·南湖模拟) 用方框中所给单词的适当形式填空。

main    guess    necessary    between    twenty

1. （1） I can only at what caused the accident.
3. （2） You shouldn't eat anything meals.
5. （3） The young people will have a party for Anna's birthday.
7. （4） The doctor says it may be for Ann to have an operation.
9. （5） We don't go out much, because we have to look after the kids. .