问题详情

Which of the following sentences expresses probability？

A．He must have picked up a cold—he"s begun to snuffle.

B．We must have a clear understanding of the problem.

C．One must have one"s own opinions and not drift with the current.

D．To be healthy one must have an adequate diet.

请帮忙给出正确答案和分析，谢谢！