若函数 是关于x的二次函数,则m的取值为( )
A:±1
B:1
C:-1
D:任何实数
关于运动和力的关系,下列说法中正确的是( )
relaxing, on, hour, useful, an, and, finish, from, favorite, after
Dear Jack,
I am very busy____Friday. At 8:00 I have math. It is not fun. The teacher says it is____ but I think it is difficult.____ that, I have P.E. at 11:00. It is easy____fun. Lunch is____12:00 to 1:00. I have Chinese at 1:20. It is my____subject. My classes____at 2:00, but then I have____art lesson for two____. It is really____.
How about you?
Yours,
Lucy
你能说出下列说法中,哪一个说明了生物能够影响环境的道理( )