The word “it” in paragraph 3 refers to __________.

Kiến thức: đọc hiểu

Tạm dịch: Từ “it” trong đoạn 3 chỉ _____.

Thông tin: In the same year, an Australian printer, James Harrison, built an ether refrigerator after noticing that when he cleaned his type with ether it became very cold as the ether evaporated.