29．—How did he break his head while swimming?

—______ my warnings, he dived straight into the shallow water．

A．To ignore

B．Ignored

C．Ignoring

D．Being ignored

办公室内的温度在空调关闭后将持续一段时间。下班前（）分钟关闭空调，既不会影响室内人员工作，又可节约大量的电能。

A.10

B.20

C.30

D.40