血清铁减低主要见于（）
A.铁利用障碍
B.铁释放增多
C.铁蛋白吸收增多
D.慢性失血
E.铁摄入过多
参考答案：D
—What were you doing when Lucy ________in yesterday?
—I had just finished my homework and ________to take a shower.
A．dropping；start
B．had dropped；started
C．dropped；have started
D．dropped；was starting
柴油机为什么要装调速器？
