对于教材,我的印象是,为凸显其专业性,有些威严的部头往往板着脸摆出居高临下的姿态,即便是面对小读者,也不过稍微缓和了一下表情,像不苟言笑的大叔生硬地咧开嘴,表皮下面的严肃却是浓得化不开。 For the textbook, my impression is that in order to highlight its professionalism, some majestic ministers often face down on the face of a downright attitude, even in the face of a small reader, but also slightly relieved expression, like a stern uncle Grin, the serious under the epidermis is thick but not open.