In which of the following situations has a contract of employment arisen?

A verbal offer of work is made to S for the possibility of duties at a specified pay rate but the employer makes it explicit that, as the need for the services is not yet certain S is free to work elsewhere

A written offer of work is made to R which specifies the services required but omits the pay rate for the job. This is not accepted by R either in writing or verbally and R does not turn up for work

A verbal offer of work is made to P at a given pay rate per hour for specified services The offer is not accepted by P either verbally or in writing but P turns up for work and performs the duties identified in the offer.

A verbal offer of work is made to Q at a given pay rate for specified services. The offer is not accepted by Q either verbally or in writing and Q does not turn up for work