3道英语单选求解释（词汇辨析类）
1.The talks might____for weeks before any concrete result is announced.A)press on B)drag on C)get bogged down D)hold out答案是B,为啥C不对呢?
2.I will hold you personally___if anything goes wrong in this project.
A)desructive B)lucrative C)diverse D)responsible答案是D,没看懂这句话...
3.A firm might sometimes sell at a loss to drive a competitor out of business,and___increase its market power.
A)therefore B)thereby C)hence D)further选B,请问therefore与thereby的区别