His _____ sister left for America yesterday. [ ]
A. young
B. old
C. big
D. elder
答案:D
空心砖砌体所用砂浆的稠度通常比石砌体所用砂浆的稠度大。
急救复苏时心外按压次数与人工呼吸次数比是()
A.30:2
B.25:2
C.20:2
D.15:2
E.10:2