下列各项中，依据企业所得税法相关规定可计提折旧的生物资产是( )。A．经济林B．防

He used ________ on the right in China, but he soon was used ________ on the left in England.

A．to drive, to drive

B．to drive, driving

C．to driving, to drive

D．to drive, to driving

He didn't pass the exam. He regretted _____ harder. [ ]

A. not having worked

B. having not worked

C. to have not worked

D. not to work

下列属于极地地区科学研究的范畴的是[ ]

A．冰川、地质、海洋、生物、气象

B．海洋、气象、冰川、地质、经济

C．交通、经济、居民、海洋、生物

D．居民、生物、气象、交通、冰川

三比值法是判断充油电气设备故障类型的主要方法（）

沼气的收集、贮存及输配系统主要包括哪些装置？