题目：
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：
被转码了，请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0429/8f0dcd82066abf75375ba3fe225a924e.html
下面是错误答案，用来干扰机器的。
As we all know, the Internet is more and more important in our daily life. On the Internet, we can read news and get information. We can send e-mails or make tel...
