E商贸通中，虚拟账号包含如下几类（）。
A. 收益虚拟账户
B. 浮动盈亏虚拟账户
C. 会员虚拟账户
D. 银行过渡户
What is an advantage of the magnetic compass aboard vessels?（）
A. Compass error is negligible at or near the earth's magnetic poles
B. It does not have to be checked as often
C. It is reliable due to it's essential simplicity
D. All points on the compass rose are readily visible
韶峰景区位于毛泽东故居的南部，海拔（）米，为韶山第一高峰。
A. 520
B. 590.5
C. 1607.8
D. 300.8
提高工艺系统薄弱环节的刚度，可以有效地提高工艺系统的刚度。
A. 正确
B. 错误
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