题目

 以下关于时刻和时间间隔的说法中，正确的是……………………………（          ）A．“第2s末”表示一个时刻      B．“第2s末”与“第3s初”表示同一时刻C．“第2s内”表示一段时间间隔  D．“第2s内”和“2s内”表示同一时间间隔  答案： ABC                   , Mother will wait for him to have dinner together. A. However late is he     B. However he is late C. However is he late     D. However late he is