新生儿复苏时血用量约()
A.5~10ml/kg
B.10~20ml/kg
C.20~30ml/kg
D.30~40ml/kg
E.40~50ml/kg
参考答案:B
Sean's strong love for his country is _____ in his recently published poems. [ ]
A. relieved
B. reflected
C. responded
D. recovered
在《验证力的平行四边形定则》的实验中,得到了如图所示的图形,图中P为橡皮条的固定点,用两只弹簧秤或用一只弹簧秤时,都将橡皮条与细线的结点拉到O点,实验中要比较的是图中_____________和_____________两个力的大小和方向,其中力_____________是实验直接测得的合力。