I’m sorry not to have replied to your letter earlier, ______, I must say , I apologize.

A．which

B．for which

C．to which

D．whom

为了防止重型设备安装后由于基础的不均匀下沉造成设备安装不合格，应对基础采取( )。

A．减振垫铁调平

B．预压试验

C．无破碎检验

D．无露筋检验