当事人在合同中既约定违约金条款，又约定定金条款时，一方违约时，另一方当事人 保护其合法权益。

A．只能依据违约金条款要求对方承担责任

B．只能依据定金条款要求对方承担责任

C．可以选择使用违约金或者定金条款要求对方承担责任

D．可以采用违约金条款加定金条款金额之和要求对方承担违约责任

John often finds herself daydreaming about boy’s and wondering what her life will be like when she gets married. According to Piaget, John is likely in which stage()

A．Sensorimotor stage

B．Preoperational stage

C．Concrete operational stage

D．Formal operational stage