高速钢的特点是高硬度、高( )、高热硬性，热处理变形小等。
A．塑性
B．耐磨性
C．韧性
D．强度
参考答案：B
上海市财政资金专户既可以开立人民币账户，也可以根据需要开立外汇账户。
Packet-switching wireless networks are preferable (1) when transmissions are (2) because of the way charges are (3) per packet. Circuit-switched networks are preferable for transferring large files or for other lengthy transmissions because customers are (4) for the (5) of time they use the network.
1（）
A．to
B．for
C．than
D．only
