A:shouldn't have gone
B:mustn't have gone
C:couldn't have gone
D:mightn't have gone
三元一次方程组3x-y+z=42x+3y-12x+y+z=6的解是____.
函数y=sin2x+π3的图象可由y=cos2x的图象经过怎样的变换得到( )
用不同状态的种子探究种子呼吸过程中释放的能量,温度计变化最大的是( )