下列各组数值是相应元素的原子序数，其中所表示的原子能以离子键结合成稳定化合物的是 

A．1与6

B．2与8

C．9与11

D．8与14

The nurse is caring for a neonate with congenital clubfoot. The child has a cast to correct the defect. Before discharge, what should the nurse tell the parents（）

A. "The cast will be removed in 6 weeks. "

B. "A new cast is needed every 1 to 2 weeks. "

C. "A short leg cast is applied when the baby is ready to walk. "

D. "The cast will be removed when the baby begins to crawl. "