直升机模型具有（）优点是其它模型飞机比拟不了的。
参考答案：垂直起落
—Why! I have nothing to write about. _______ that you want me to say?
—Your summary for this term and holiday schedule.
A．What is it
B．What it is
C．What are they
D．What they are
大量咯血指的是（）
A.每日咯血量100ml
B.每日咯血量200ml
C.每日咯血量300ml
D.每日咯血量在500ml以上
E.一次咯血量80ml
