The nurse teaches a mother how to provide adequate nutrition for her toddler, who has cerebral palsy. Which of the following observations indicates that teaching has been effective

A. The toddler stays neat while eating.
B. The toddler finishes the meal within a specified period of time.
C. The child lies down to rest after eating.
D. The child eats finger foods by himsel

警车A停在路口，一违章货车B恰好经过A车，A车立即加速追赶，它们的v-t图象如图所示，则0～4s时间内，下列说法正确的是（　　）

A．A车的加速度为5m/s²

B．3s末A车速度为7m/s

C．在2s末A车追上B车

D．两车相距最远为5m