At ______, photography is a chemical process, during which a light-sensitive material is altered when exposed to light.

She hired a lawyer to investigate, only to learn that Gabriel had removed her name from the deed.The infinitive verb phrase “only to learn ” is used ____.

Ifasubstanceisdissolvedinwaterorheated，itmay（）agas.

Theministeroffinanceisbelieved_____ofimposingnewtaxestoraiseextrarevenue.

My mother was determined to help those in need and she would have been immensely proud of what has been achieved these last 20 years. The italicized part in the sentence expresses _______.