He _______ more visits to his parents.He has been regretting not doing so since they passed away.

A．should pay

B．would pay

C．should have paid

D．would have paid

如果生产过程中存在规模报酬递增，则意味着当所有要素的投入同比例增加时，产量将( )。

A．以比要素增幅大的幅度增长

B．保持不变

C．以比要素增幅小的幅度增长

D．减少