how to 可以引导宾语从句吗?例如I want to find out that how to protect our environment?

不行的
how to do sth是动词不定式,不能用that引导.去掉that是一个合法的句子吗？如果不是，应该怎样，去掉that就是一个带有连接副词的动词不定式，不是句子。如要改成句子，就是以连接代词或副词作为引导词的宾语从句。I want to find how we can protect our environment.用宾语从句我懂，我就想知道I want to find outhow to protect our environment?这样有没有问题，疑问句里 how to protect our environment.? 是否可行完全正确。就是动词不定式前加上特殊疑问词。再如：where to go , how to do it, what to buy, which one to choose.等