They are having a class in the History of the Communist Party of Chian.请问一下in在里面起什么作用

when they are having a good they are all having a good time They are having a good time.中文 They are having a Chinesd lesson . They are all having a good time they are having meal/a meal/meals? ( )2.They ________ a Music lesson.A.having B.are having C.are have they are (having a PE lesson.)对括号提问? they are having a meeting的同义句 what a good time they are having的意思 [are,good,having,time,a,They(.)]连词成句 They are having a very happy __ (life). 翻译：他们正在通电话 ,填空：They are having a [ ][ ] 补全单词 Look!They are having a piano l_____ They are having a soccer m______ on the playground. they are having a good time_____the heat.填什么 They are having a talk face to face 翻译 They are having a biology lesson now 变成同义句 They are () a biology () now