—I'm dead tired. I can't walk any further, Jenny.
—____, Tommy. You can do it.
A:No problem
B:No hurry
C:Come on
D:That's OK
胚胎在母体内发育的场所是( )
已知正三角形OAB中,点O为原点,点B的坐标是(-3,4),点A在第一象限,向量m→=(-1,0),记向量m→与向量OA→的夹角为α,则sinα的值为( )