Unit 4 I used to be afraid of the dark.语法used to 的用法1.“used to do sth”意为“过去常常做某事”，表示过去的习惯动作或状态，现在已不发生或不存在。She used to be thin,but now she is fat.The young man used to wear glasses,but now he doesnt wear glasses.2.带used to的句子的各种句式的构成：(1)肯定句的构成是:主语+ used to do sth. He used to play basketball after school.(2)否定句的构成是:主语+ didnt use to do sth. She didnt use to have long hair.(3)一般疑问句构成是: Did+主语+use to do sth? 肯定回答是： Yes,主语+did 否定回答是：No,
