A:秦朝
B:汉朝
C:宋朝
D:明朝
镁和铝分别与等浓度、等体积的过量稀硫酸反应,产生气体的体积(V)与时间(t)关系如图.反应中镁和铝的关系说法正确的是( )
It's six o'clock in the afternoon. It's time for 1!Jenny and Li Ming are2. Jenny's mother is 3 in the kitchen. Jenny and Li Ming help Mrs. Smith 4 the vegetables. After dinner, Mrs. Smith washes the 5 dishes. Li Ming dries the dishes.
已知函数y=fx的导函数y=f'x的图象如图所示,则关于函数y=fx,下列说法正确的是 ( )
如图,AC是电线杆AB的一根拉线,测得BC的长为6米,∠ACB=50°,则拉线AC的长为( )