一个音节可以分成（）种构成成分，其中（）是音节必有的成分。
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直线轨道的方向和轨面前后高低应在接头前后各（）m内检查测量。
On all vessels equipped with refrigeration units of over 20 cubic foot capacity, （）.
A. a gas mask suitable for protection against each refrigerant used, or a self contained breathing apparatus must be provided
B. it is the sole responsibility of the chief engineer to ascertain that all members of the engineering department are familiar with the use of gas masks or breathing apparatus
C. spare charges shall be carried for at least 50% of each size and variety of gas masks and/or self contained breathing apparatus
D. all of the above
程控机房应有防静电措施，其空气的静电感应电压不得超过（）V。
A. 2000
B. 3000
C. 2500
D. 1800
计算题：有台流量为3.2m3/s的水泵，问它运行5h共排放了多少吨水？
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