根据所给汉语和句子意思，用英语补全句子。

1.As we all know, waste water and gas ______________________(对……有不良影响)the environment.

2.A pair of pandas __________________(赠送)to Australia months ago, which represents the friendship between Australian and Chinese people.

3.---Do you often use Baidu ?

---Yes, it’s one of ____________________________(最受欢迎的)Internet search engines.

液态烃C₅超标，在生产民用液化气时会引起（）。

A、液体残留多

B、烧不着

C、火焰发飘

D、热值低