The comments the expert made _____ stock market bothered Bill greatly, _____ him sleepless all night.[      ]

A.  concerning; making  

B.  be concerning; which made

C.  concerned; made      

D.  to be concerning; made

哪种物理灭菌法是最有效的，保存的使用期限长。（）

A、煮沸灭菌法

B、蒸笼灭菌法

C、高压蒸汽灭菌法