9.looks,因为前面主语说的是一条牛仔裤,所以用单数10.look.因为这里的主语是The jeans类指,牛仔裤的总称,所以用复数
9. This pair of jeans looks cool. == it looks cool.10. The jeans look cool.== they look cool.
9. looks(主语是pair,单三)10.look(主语是jeans,复数) 供参考。
我只知道第二个填looks