He fell off the bike and hurt his leg yesterday._______, he had to stay at home for two or three months.
A:So that
B:As a result
C:Such as
D:Because of
如图所示,实线为一组方向未知的匀强电场的电场线,虚线为某带电粒子经过该区域时的运动轨迹,a、b为其轨迹上的两点。若该粒子运动过程中只受电场力作用,下列说法正确的是( )
如图,在一个半径为6cm圆形纸片上,挖去一个半径为r cm的圆,若余下圆环面积为11π,则r为( )
下列关于人和被子植物结构层次的叙述,正确的是( )
54÷6=____
54÷9=____