【单选题】你认为主人公最后为什么选择自首而不是杀死对方
【单选题】The headmaster introduced ______ to the German visitors before the welcome party.
【简答题】The head called on the students to r___________ money for the poor boy.
【单选题】The headmaster _______ our holidays by a week.
【判断题】由达西公式可知,管路的水头损失与断面平均流速的2次方成正比。