It is risky to hike in these unstable weather conditions. Here the infinitive 'to hike' is used as -

• বাক্যে ব্যবহারের দিক দিয়ে structure অনুযায়ী infinitive - noun, adverb or adjective হয়ে থাকে।
- It is risky to hike in these unstable weather conditions. Here the infinitive 'to hike' is used as - Noun.
- এখানে introductory 'it' এর subject হিসাবে 'to hike' হচ্ছে noun.

• Infinitive as Adjective:
- It has no possibility to appear. Here the infinitive 'to appear' is used as - an adjective.
- কারণ এখানে বাক্যস্থিত noun word 'possibility' কে 'to appear' modify করছে।

• Infinitive as Adverb: 
- He worked late to meet the project deadline. Here "to meet" is used as -an adverb.
- Here "to meet" describes why he worked late.
- অর্থাৎ, এটি woked verb টি কে modifiy করছে।

• Infinitive হচ্ছে verb এর base form অথবা to + base form.
- Infinitive দুই রকম হতে পারে-
১. To-যুক্ত infinitive. যেমন: To err is human. এবং
২. To-বিহীন infinitive. যেমন: let me go.
- To-বিহীন infinitive form-কে bare infinitive বলা হয়।