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
