反映铅在体内含量的指标是()。
A.网织红细胞
B.尿ALA
C.尿粪卟啉
D.血铅
E.游离原卟啉
参考答案:D
下列各组物质互为同系物的是
A.CH3CH2Cl与CH3CH2CH2Br
B.CH3CH2Cl与CH3CHCl2
C.HOCH2- CH2OH与HOCH2 -CH2- CH2OH
D.CH2O和C2H4O2
A capsized small sail vessel is best righted when what part of the vessel is downwind?()
A.Stern
B.Bow
C.Centerboard
D.Mast