The father _____ his son to buy him a car if he goes abroad to further study.[ ]

A. agrees

B. promises

C. allows

D. permits

空心砖墙底部宜砌（）。

A．1皮混凝土小型空心砌块

B．2皮混凝土大型空心砌块

C．1皮烧结普通砖

D．3皮烧结普通砖