I'm trying to write:
While construction began in China, people hadn't thought of the pollution.
Is this an accurate use of the grammar: shi4 ... de
Shorten as much as possible as long as the meaning remains the same, "中国的建设开始的时候" can be reduced to : "中国的建设开始时" (avoid two 的 in the same sentence)
人人(everyone) - use '人们'(people) as the subject instead is better.
人们是不以为过 - the verb '是' should be omitted because 不以为 (didn't consider) is also a verb, so the sentence should be "人们不以为过"
人们不以为过 - you tried to use '不' to indicate 'had not' but the correct term here should be 未曾 or 没有
人们没有以为过 - You try to use '以为' for 'considered' but the primary meaning of '以为' is 'thought' , the correct word for 'considered' is 考虑
(a) 人们没有考虑过环境污染的。 -- 境污染的 is an adjectival phrase, you need a noun after it, for example. 人们没有考虑过环境污染的问题。
(b). You can simply use '环境污染' (environmental pollution) as the noun and write "人们没有考虑过环境污染。"
Add word particle '并' before the verb '没有考虑' to emphasize ' something should had been done but hadn't)
"没有考虑过"(had never considered) implies people deliberately ignored the problem; replace 过 with 到 and write "没有考虑到" (had not considered) implies it was an oversight