— Honey, this is a present for your birthday.

— Ah! A pair of shoes, a well-known brand — Nike! I think it must ______ comfortably.

A．be worn

B．be wearing

C．have worn

D．wear

人类的生产和生活都离不开O₂。有关O₂的认识正确的是

A.木炭在空气中燃烧比在O₂中燃烧更旺

B.工业上可以通过分离液态空气制取O₂

C.O₂易溶于水，不能用排水法收集

D实验室中可用加热分解水来制取O₂