1.In some states of America,children must stay in school until they are sixteen.
问题描述：
1.In some states of America,children must stay in school until they are sixteen.
In some states of America,children_____ _____school until they are sixteen.
2.Mary works very hard at schllo.Her teacher often praises her.
Mary is often praised _____her hard _______.
3.The recitation was kind of boring and I liked the cross talk better.
The recitation was _____ ______boring and I preferred the cross talk.
答
1.mustn't leave (not …… until 是固定结构：直到……才……）
2.for work（work 在这里是名词）
3.a little/a bit /kind of这三个短语都是 “有点的” 意思.