双块式轨枕高度允许误差为（）mm。
A、1
B、3
C、5
参考答案：B
若多项式x2＋x10＝a0＋a1(x＋1)＋…＋a9(x＋1)9＋a10(x＋1)10，则a9＝________.
Tom_______two of his classmates_______invited to the party.
A．as well as; was
B．as good as; were
C．and; have
D．as well; has been
