下列哪一项试验检查对确定体内缺铁的诊断意义最大:()
A.血清铁降低
B.网织红细胞降低
C.血清总铁结合力升高
D.骨髓贮存铁缺乏
E.红细胞是小细胞低色素型
参考答案:D
Peter was so tired that he went to bed early , ___.
A.leaving his homework unfinished
B.leaving his homework being unfinished
C.leaving his howework unfinishing
D.to leave his homework unfinished
卧式车床主轴箱常用的制动装置有()。