无菌过滤时要选用合适孔径的滤芯,大多采用()孔径的滤芯,以滤除酵母菌和一般污染菌,基本达到无菌要求,而不影响啤酒风味。
A、0.2μm
B、0.45μm
C、0.8μm
参考答案:B
下列属于等位基因的是 [ ]
A.A与b
B.Y与y
C.M与M
D.n与n
Only after staying in England for a few weeks did Li Lei become used ____
Chinese.
A.to not speaking
B.not to speaking
C.to not speak
D.not to speak