Mr. Li is a ________ .He ______ us how to swim.A．teaches, teachesB．teacher, teacherC．teacher, teachesD．tescher, teach
Are you sometimes a little tired and sleepy in the early afternoon? Many people feel this way after lunch．They may think that eating lunch is the cause of the sleepiness．Or，in summer
Let your little brother play your toys as well, Alice — you must learn to ______. A. support B. spare C. share D. care
She feeds the baby____milk and hay____her cattle. A.on;to B.to;on C.with;to D.on;with
右图为某粒子（原子或离子）的结构示意图（其中n≠0），请回答下列问题。 ①n的最大值为___________ ②若该粒子带两个单位的负电荷，则其对应的化学
如图所示，实线是某时刻的波形图，虚线是0.2 s后的波形图．(1)若波沿x轴负方向传播，求它传播的可能距离．(2)若波沿x轴正方向传播，求它的最大周期
已知平面向量，，满足||=，||=1，•=﹣1，且﹣与﹣的夹角为45°，则||的最大值等于（）A． B．2 C． D．1
某种毒素因妨碍细胞呼吸而影响生物体的生活,这种毒素可能作用于的细胞器（ ） A、核糖体 B、内质网 C、线粒体 D、细胞
