将下列句子合并成带有定语从句的复合句。

将下列句子合并成带有定语从句的复合句。
12．We visited the singer yesterday． 　　Her performances we all like very much． 13. The old worker is still working hard with us． 　 His hair has turned gray． 14. The bike was not good．You wanted to buy it． 15. The medicine didn't help me． 　　Dr. Chang had given it． 16．The exercise is wrong．We did it last night． 17．The woman is here now． 　　You were talking about her．