单项选择题
A. they are to be back before nine in the evening B. they ought to be back before nine in the evening C. they be back before nine in the evening D. they had to be back before nine in the evening
A. Severe Thunderstorms and Damages. B. Weather Forecasting and Life-threatening. C. Science Advances and Nowcasts. D. Available Data and Nowcasts.
A. when they were going to die B. because they were thirsty C. because there was little salt D. because they were short of water