To _____, in the school art festival next week, the quiet boy will have an opportunity to attract public attention.

A．our credit

B．his delight

C．his astonishment

D．his credit

循环系统的关键设备是（），通常称之为钻机的心脏。

A.钻井泵

B.转盘

C.水龙头

D.绞车