如图所示的各大洲轮廓,按照南美洲、大洋洲、非洲、欧洲排列顺序正确的是
A.①②③④
B.③④①②
C.①③②④
D.③①④②
答案:A
Cigarettes and alcohol do such ________ great harm to health that they can easily cause ________
weakening of our bodies.[ ]
A. a; /
B. /; the
C. a; the
D. /; /
以下哪些指标是参数( )
A.β
B.μ
C.ρ
D.σ