A:①为白细胞,能够吞噬病菌和异物
B:②的体积最小,能止血和加速凝血
C:③的数量最多,能够运输氧气
D:①、②、③中只有②没有细胞核
求作:Rt△ABC,使∠C=90°,∠A=∠α,AC=a.
—I hear that a modern church is to be built near our school.
—I'm afraid that it doesn't ________the surroundings.
如图,AB∥CD,BE交CD于点F,若∠B=50°,则∠DFE的度数为( )