【单选题】Linda spends her entire budget and consumes 15 units of x and 19 units of y. The price of x is twice the price of y. Her income doubles and the price of y doubles, but the price of x stays the same. I...
【单选题】(6~8题共用题干)患儿,出生时皮肤苍白,心率40次/分,无呼吸,四肢略屈曲,弹足底无反应。患儿Apgar评分为
【单选题】下列4组组成不同的混合溶液,当Pb(s)插入各组溶液时,金属Sn有可能被置换出来的是(已知 φ Θ (Sn 2+ ,Sn)=-0.136V; φ Θ (Pb 2+ ,Pb)=-0.126V)
A.
a(Sn 2+ )=1.0,a(Pb 2+ )=1.0
B.
a(Sn 2+ )=0.1,a(Pb 2+ )=1.0
C.
a(Sn 2+ )=1.0,a(Pb 2+ )=0.1
D.
a(Sn 2+ )=0.5,a(Pb 2+ )=0.5
【单选题】已知3x 2 ﹣2y+5=7,则9x 2 ﹣6y﹣3=( ) [ ]
【单选题】三角形螺纹的牙型角α=_______,而梯形螺纹的牙型角α=_______