不同年龄对缺氧的耐受性差别很大,幼年时对缺氧耐受性大,而老年人对缺氧耐受性降低。
参考答案:对
_______ the beginning of 1999, the popularity of MP3 has increased greatly.[ ]
A. In
B. Since
C. To
D. At
S-T段在基线上可有偏移,其正常偏移值为()
A.抬高<0.5mm,压低<1mm
B.抬高<1mm,压低<0.5mm
C.抬高<2mm,压低<1mm
D.抬高<3mm,压低<2mm
E.抬高<3mm,压低<2.5mm