问题
选择题
the safety of gas, the government has checked the city's gas supply system thoroughly.[ ]
A. To ensure
B. Ensuring
C. Having ensured
D. To have ensured
答案
A
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the safety of gas, the government has checked the city's gas supply system thoroughly.[ ]
A. To ensure
B. Ensuring
C. Having ensured
D. To have ensured
A