A minus symbol '-' means the same as 'not', so if you want to learn about birds but you do not want any information about sparrows, you could type 'bird - sparrow'.

减号“-”与“不”意思一样，所以如果你想要学习鸟类而又不想要有关麻雀的信息，你可以输入“鸟”-“麻雀”。