thirty怎么读,thirty是什么意思

外研版一年级起点七年级英语上册there are thirty students in my
科普版五年级下册lesson7it'sseventhirty-five课件ppt
七年级英语上册_module_3_my_new_school_unit_1
module3 unit1 there are thirty students in my class(共41张ppt)
外研版七年级英语上册module3 my school unit1 there are thirty