题型:问答题 简答题 完成下列算式。1. three + nine = ____________2. ____________ + ten = sixteen 3. twenty - ____________ = eighteen 4. four + thirteen = ____________5. eight + ____________ = nineteen 6. ten + seven = ____________ 查看答案
题型:问答题 简答题 长为L粗细均匀的圆柱体,其轴线与直角坐标系x轴重合,底面过原点且与yOz平面平行,如图所示,圆柱体在yOz平面内质量均匀分布,在x方向密度均匀增加,则圆柱体重心位置坐标(xc,yc,zc)为( )A.yc=0,,zc=0,xc>B.yc=0,,zc=0,xc=C.yc=0,,zc=0,xc<D.无法判断 查看答案