picture book的复数形式怎么写

The professor pored over the picture book in silence.教授默默地凝视着画册.I gave a picture book to each of the boys.我给了每个男孩一本小人书.I have a picture book.我有一本图画书....

picture book的音标：picture book的英式发音音标为：['piktʃə buk]picture book的美式发音音标为：['pɪktʃɚ bʊk]...

n.图画书...