用藻酸盐印模材取印模后要立即灌模型。因为印模材（ ）。
A．吸水收缩
B．失水收缩
C．失水膨胀
D．与模型不易分离
E．影响模型强度
参考答案：B
The children went home from the grammar school, their lessons __________ for the day.
A．finishing)
B．finished
C．had finished
D．were finished
促使法国参加美国独立战争的关键性战役是什么？
