茎枝生长的决定因子是遗传，茎源根系生长速率高于实生根系.
参考答案：错
牡丹皮生用可（）
A.散热凉血
B.清热泻火
C.活血散瘀
D.凉血解毒
E.凉血止血
Tom has been in the factory _________he left school.
A．when
B．since
C．as soon as
D．whether
