上腔静脉的属支是（）
A.胸廓内静脉
B.椎静脉
C.甲状腺下静脉
D.奇静脉
E.锁骨下静脉
参考答案：D
可引起血清铁降低的情况有（）。
A.慢性感染
B.缺铁性贫血
C.恶性肿瘤
D.溶血性贫血
E.再生障碍性贫血
Sally worked late in the evening to finish her report _______ her boss could read it first next morning.
A．so that
B．because
C．before
D．now that
