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参考解析：
刷刷题刷刷变学霸
举一反三
【多选题】进水渠设计的原则是在合理的开挖方量下尽量减小水头损失，为此（ ）。
A.
进水渠纵断面应做成正坡
B.
进水渠必须转弯时，转弯半径不小于3倍渠底宽度
C.
进水渠横断面尺寸应满足不冲不於流速要求
D.
进水渠在平面上宜布置成直线
E.
进水渠纵断面应做成平坡或底坡较小的反坡
【单选题】C Federal regulators Wednesday approved a plan to create a nationwide emergence alert (警报) system using text messages delivered to cell phones. Text messages have exploded in popularity in recent year...
A.
To warn people of emergencies via messages.
B.
To popularize the use of cell phones.
C.
To estimate the monthly number of messages.
D.
To promote the wireless industry.
【单选题】C Federal regulators Wednesday approved a plan to create a nationwide emergence alert (警报) system using text messages delivered to cell phones. Text messages have exploded in popularity in recent year...
A.
the US federal government
B.
mobile phone users
C.
the carriers themselves
D.
the law of the United States