纯培养体
参考答案：经过反复分离纯化后，在平板上挑取的由单个菌落繁衍的微生物后代。
The T-shirt costs me 35 yuan, which is really a bargain, because they are _____.
A．on show
B．on sale
C．in store
D．in advance
肌肉收缩的形式有()
A．单收缩
B．等长收缩
C．完全强直收缩
D．等张收缩
E．不完全强直收缩
