植物的分类:植物分类的重要依据是_____、_____和_____的形态结构。植物可分为_______和_______两大类。
花;果实;种子;无种子;有种子
I will be surprised if you can get Calvin, who is very busy, ______these tickets for you.
A.buy
B.buying
C.buys
D.to buy
一横波沿绳子传播时的波动方程为y=0.05cos(4πx-10πt)(SI)则下面关于其皮长、波速的叙述,哪个是正确的?()
A.波长为0.5m
B.波长为0.05m
C.波速为25m/s
D.波速为5m/s