--Well,it's hard to say.But I heard him loudly when I passed by just now. .
A:speak
B:to speak
C:spoken
D:speaking
若将细菌放置于固体培养基上,它会繁殖并形成菌落,如图所示。下列实验可以用来检验两种抗生素杀菌效果的是( )
关于“南北对话”的叙述,正确的是( )
用科学计算器计算:135× 13 sin13°≈____.(精确到0.1)
下面表示骨、关节和肌肉的模式简图中,最准确的是( )