No one knows for certain what happened, but it's a fair bet that it was not an accident.
没有人知道究竟发生了什么,但几乎可以肯定这并非意外。
A French physician decided to get rid of the wild rabbits on his own estate and introduced myxomatosis.
一位法国内科医生决定除掉自己庄园内的野兔子,于是引进了这种多发性粘液瘤疾病。