脐带先露或脱垂引起胎儿缺氧，以下哪种胎先露最轻：
A．肩先露B．单臀先露C．足先露D．头先露E．颏先露
参考答案：A
According to their predictions, more than 20,000 tourists are expected by the hotel this year.
A．to be received
B．to receive
C．receiving
D．received
无尿是指24h尿量少于（）
A.50ml
B.100ml
C.200ml
D.300ml
E.400ml
