A:developing
B:developed
C:develo
D:develo
合理计算
小敏在今年的校运动会跳远比赛中跳出了满意一跳,函数h=3.5t-4.9t2(的单位:秒,h的单位:米)可以描述他跳跃时重心高度的变化,则他起跳后到重心最高时所用的时间是( )
给下面的句子选择合适的答语。
①Happy birthday! ____ A. Two books.
②How old are you? ____ B. Thank you.
③How many books? ____ C. You're welcome.
④Let's eat the cake. ____ D. I'm 10.
⑤Thank you. ____ E. Great.
设a→=(1,1,-2),b→=(x,y,z)若x2+y2+z2=16,则a→·b→的最大值为____