副 fù - measure word

一副 [yī fù], measure word, means a set or a pair of; a facial expression

一副 [yī fù] a set or a pair of

一副担架 [dān jià] a stretcher

一副对联 [duì lián] a couplet

一副耳环 [ěr huán] a pair of earrings

一副耳机 [ěr jī] a pair of earphones

一副拐杖 [ɡuǎi zhànɡ] a pair of crutches

一副假牙 [jiǎ yá] a set of dentures

一副镜框 [jìnɡ kuànɡ] a mirror frame

一副麻将 [má jiānɡ] a mahjong set

一副扑克牌 [pū ke pái] a deck of playing cards

一副手套 [shǒu tào] a pair of gloves

一副手镯 [shǒu zhuó] a pair of bracelets

一副望远镜 [wànɡ yuǎn jìnɡ] a pair of binoculars

一副相框 [xiānɡ kuànɡ] a photo frame

一副象棋 [xiànɡ qí] a set of Chinese chess pieces

一副眼镜 [yǎn jìnɡ] a pair of eyeglasses

一副 [yī fù] a facial expression

一副愁眉苦脸 [chóu méi kǔ liǎn] a sad look

一副笑脸 [xiào liǎn] a smiling face

一副好心肠 [hǎo xīn chánɡ] a kind heart

Though 一对 [yī duì] and 一双 [yī shuānɡ] both mean "a pair of" —双 [yī shuānɡ] is largely used for a pair of body organs, limbs, or two things of the same kind often used together; whereas 一对 [yl dui] is used for two people or two things that are seen together and associated with one another. One exception is 裤子 [kù zi, pants]. The measure word for 裤子[kù zi] is 一条 [yī tiáo ]. For 手套[shǒu tào, gloves] and 耳环[ěr huán,  earrings], 一副/付 [yī fù] is more often used than 一双 [yī shuānɡ].