我是钟先生的同事，我是杜衡，钟先生今天要开会没有办法亲自带您去看房所以今天有我来代替他为您提供服务

I am a clock the Sir's colleague, I be a Du Heng and today of Sir of clock want to hold a meeting to have no way to take you to see building in person so today have me to replace him to provide service for you

用短句容易交流，如：
Excuse me, Mr.Zhong is in business now and I will replace him.Any problem ,please do not hesitate to tell me.