酶免疫法()
A.激发光
B.发射光
C.两者均有
D.两者均无
参考答案:D
A.磁感线上每一点的切线方向就是该点的磁场方向
B.磁感线一定从磁体的N极出发,到S极终止
C.任何磁场的磁感线都是闭合曲线,磁感线在空间可能相交
D.磁感线密处磁场强,磁感线疏处磁场弱
-When is your father's birthday?
-It's on _ _ .
A.December twenty -two.
B.October twenty-second.
C.December twenty-second.
D.November twenty-two.