On 1st September, Helen told Kelvin that she would let him have her Antique Rolex watch for HK$200,000. However, Kelvin told Helen that he would buy the watch at HK$120,000 only. Kelvin's suggested price was refused by Helen at the same time.

On 2ndSeptember, Kelvin telephoned Helen and said that he had changed his mind and that he wanted to accept Helen's offer. However, Helen told Kelvin that she had already sold the watch to somebody else.

Advise Helen if there was a contract between her and Kelvin.