-Mary,could you tell me if your mother        our school sports meeting tomorrow?

-I think she will come to school if she         free.[ ]

A. will take part in; will be

B. takes part in; is

C. will take part in; is

D. takes part in; will be

下列对于要约的表述，错误的是( )。

A．要约是一种意思表示

B．要约是以缔结合同为目的

C．要约有具体确定的内容

D．要约约束受要约人而非要约人