《铀矿冶炼安全规程》中有关竖井施工的安全生产要求，说法正确的是()。

A.关闭井盖门之前，禁止装卸吊桶 

B.竖井施工应采用单层吊盘作业 

C.井下作业人员的工具应随手携带 

D.吊盘上有石碴坠落时应及时通知井底

The old man was so angry and spoke so fast that none of his children understood ____ he said meant.

A．that, that

B．what. what

C．what

D．that