下面的()可以作为停留时间分布密度函数E(t)。
A.A
B.B
C.C
D.D
参考答案:A
About 698,000 laptops were sold in China in______second quarter, _____12.1 percent increase from a year ago.
A.a; a
B.the; a
C.the;the
D.a; the
颈椎椎管前后径的正常下限是()
A.15mm
B.14mm
C.13mm
D.12mm
E.11mm