一句英文 用法

句中文法是正確的，只不過這句中將句中的不定詞(infinitive)，作為形容詞（the complex的補語），意思是”to be bult”是一個Ajective Infinitive用作補充對subject的形容。

eg. The house is not to let(or to be let)：這房子不是要出租的
　　He is not to blame(or to be blamed) for this他不該為此而受責

若你想了解詳細點，你可以從英文文法書中，找形容詞不定詞(Adjective Infinitive)的篇章看。

希望你明白我的解釋

i think the best point of the answer is to explain what tense it is. If he/she could explain more about adjective infinitive, the answer would be better and more worth to be best answer.

我諗呢個就係英文 tense 時態有趣嘅地方, 尤其建築唔係一朝一夕

如果將 A petrochemical complex is (to be built) here. 中括弧部份抽出, 就會剩下 A petrochemical complex is here. 即是肯定石油化工設施在這裡; 所以插入 to be built 就是表達石油化工設施肯定在這裡興建但它尚未開始動工

例：
A petrochemical complex is (being) built here.
即是已經動工 (正在興建中)

A petrochemical complex will be built here.
只表示將會興建但又不代表一定會動工

A petrochemical complex has to be built here.
只表示有需要興建, 莫講會否動工

A petrochemical complex has (been) built here.
興建已完成

有to be done.eg:Work is needed to be done!
有to be finished.eg:Project is to be finished in a week.
點解沒有to be built?
What the guy above said was right.Its passive and work needed to be done by someone.Otherwise it will not happen at all.
You can turn around and say.Those people are going to build a Petrochemical complex here.
Hope that helps a bit