The pen writes well.the ads are aimed at them.为什么后者用被动而前者不用?

The pen writes well.the ads are aimed at them.为什么后者用被动而前者不用? many ads are aimed------(special) at teenagers. Many ads are aimed specificaly at teenagers. The pen ___well.It ___well.为什么填writes和sells,而不是被动啊? The pen writes well though it doesn't cost much. at the library 和in the library 有什么区别?什么时候用前者?什么时候用后者? The books sell well.为什么不用被动语态 为什么是this pen writes well At the b_____of the film.there are some ads The pen writes —— The boy (writes/to write)the letter needs a pen.为什么用to write The pen │writes smoothly.为什么加S