单项选择题
A.Bad weather. B.Human error. C.Breakdown of the engines. D.Failure of the communications system.
A.The crop’s blooming period is delayed. B.The roots of crops are cut off. C.The topsoil is seriously damaged. D.The growth of weeds is accelerated.
A.His father caught a serious disease. B.His mother passed away. C.His mother left him to marry a rich businessman. D.His father took to drinking.