By this time,a Lancaster bomber in reasonable coindition was rare and worth rescuing
问题描述：
By this time,a Lancaster bomber in reasonable coindition was rare and worth rescuing
最后rescue为什么是ing 形式,如果说是be worth doing,那么be动词在哪里,只有一个worth doing啊,这到底是怎么理解
答
be 就是前面的 was
rare跟worth rescuing是并列的.