Why are some tattooists called" responsible"？
A. They want to prevent their customers from suffering latch
B. They refuse to tattoo areas that cannot normally be covered up.
C. They are clean and careful in their work.
D. They carefully consider their customers' needs.
My telephone number is 54362Have you ______？
A. written them down
B. written down it
C. written it down
当曝气池的水力停留时间较短如（）h左右，应以最大时流量作为曝气池的设计流量。
A. 1
B. 1.5
C. 2.5
D. 2
车行道下的污水管道最小覆土厚度一般不宜小于（）m。
A. 0.5
B. 0.7
C. 0.9
D. 1
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