12 现在完成进行时 The present perfect continuous

12.2 the present perfect continuous and the present perfect simple

11.5 现在完成时和过去时 the present perfect simple and the past simple

11.4 gone和been gone and been

11.2 规则过去分词 regular past participles

11 现在完成时 the present perfect simple

10.2 过去进行用于场景设定 the past continuous for scene-setting

10 过去进行 the past continuous

9.2 用be的一般过去时疑问句 questions in the past simple with be

09 一般过去时疑问句 past simple questions