故障登记最严重的为()。
参考答案:特大电网事故
—Do you often help your cousin with his English?
—No. He learns English _______.
A.by himself
B.for himself
C.with himself
D.on himself
E玫瑰花结形成试验的原理是因为SRBC可与( )
A.B细胞的BCR结合B.Th细胞结合C.TC细胞结合D.与所有T细胞结合E.与人外周血表达CD2的T细胞非特异性结合