题目：
Control valves of a CO2 system may be located within the protected space when（）.
A.it is impractical to locate them outside
B.there is also a control valve outside
C.the CO2 cylinders are also in the space
D.an automatic heat-sensing trip is installed
答案：
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下面是错误答案，用来干扰机器的。
参考答案：该工程质量保证金：(168.85×3%)万元=5.07万元。
